GB2478855A

GB2478855A - Heat resistant fabric

Info

Publication number: GB2478855A
Application number: GB1104580A
Authority: GB
Inventors: Michael Fisher; Alan Brown
Original assignee: Toray Textiles Europe Ltd
Current assignee: Toray Textiles Europe Ltd
Priority date: 2010-03-19
Filing date: 2011-03-17
Publication date: 2011-09-21
Anticipated expiration: 2031-03-17
Also published as: WO2011114107A1; GB2478855B; GB201004693D0; EP2547814A1; GB201104580D0

Abstract

A double layered or double weave fabric for use in molten metal processing industries such as smelting and welding comprises fluoropolymer yarn, preferably PTFE, and a non-fusible fibre yarn, preferably aramid, and may be woven or knitted. The front face layer preferably comprises PTFE weft and warp yarns, and the rear face layer preferably comprises a mix of PTFE and aramid yarns for both warp and weft. Some PTFE weft picks of the back layer may be moved to the front layer to link the layers so that the front face remains all PTFE. The fabric may be shrunk, the differential shrinkage of PTFE and aramid causes puckering of the preferably predominantly aramid back layer to trap air to enhance heat insulation. The front PTFE face has a flat closed surface and metal spatter impacting it rolls or slides off readily. The fabric preferably has a weight of 350-650g/m2) a weft density of 25-60 threads/cm and a warp density of 35-65 threads/cm. The PTFE yarn preferably ha a denier of 300-1500 and the fabric may pass the EN ISO 11612:2008 and EN ISO 1611:2007 standards. The fabric may be used for protective clothing, protective screens, and covers for computers and electrical appliances.

Description

Heat Resistant Fabric

Field Of The Invention

The present invention relates to a fabric for use in molten metal processing industries such as smelting, forging, casting, cutting and welding.

BacKground

Foundry workers and welders are exposed to high temperatures and hot, molten metal splash. In smelting, forging, casting, cutting and welding, personal protection garments are used to protect the workers from serious burns. Additionally, in cutting and welding, screening curtains are used, to offer further protection to non-welders in the vicinity.

Due to the "hands-on", practical work of a foundry worker or welder, the garments need to have good mechanical properties and be durable. When garments wear quickly or tear heat and flame protection is significantly reduced and the comfort of the garment for the user is diminished.

One current solution is to make personal protection garments for hot metal workers from a thick woollen fabric. The wool is made suitably thick, such that when molten metal hits the garment, it starts to burn through the fabric, but will not burn all the way through to the skin; protecting the wearer from burns. The required thickness of the fabric results in heavy personal protection garments.

An alternative to wool is an aramid yarn, which is a non-fusible fibre yarn sold, for example, under the trade name Nomex®. Again, these garments are relatively thick, so that the molten metal chars through some of the fabric, but does not reach the skin. This of course results in heavy personal protection garments for foundry workers and welders, which is uncomfortable for the worker wearing them.

Summary Of The Invention

At its most general, the present invention proposes that fluoropolymer yarn and non-fusible fibre yarn be used to form a single fabric, which is a double layered fabric. In this way, the single fabric can provide a fluoropolymer yarn "outer" layer to prevent molten metal splash from staying at the site of impact, and a non-fusible fibre yarn "inner" layer to provide heat and flame resistant properties.

The combination of these two types of layers in the double layered fabric structure provides significant advantages in achieving resistance to molten metal splash. In particular, the interconnected structure that characterises a double layered fabric permits one of the layers (the fabric face) to be entirely fluoropolymer yarn to shed molten metal splash with the other layer (fabric back) being mainly non-fusible fibre yarn to provide heat resistance.

In a first aspect, the present invention provides a fabric comprising a fluoropolymer yarn and a non-fusible fibre yarn, wherein the yarns form a double layered fabric.

An advantage of a double layered fabric is that the two layers are integral to the same fabric, i.e. they are connected together by a binding thread moving from one layer to the other layer, such that there is no need for a bonding layer or other bonding means in order to provide structural integrity. Thus, the invention is not concerned with fabrics where a bonding layer or other bonding means (e.g. needle punching) is needed to form a single fabric.

Similarly, the skilled reader will understand that the present invention is not concerned with fabrics having two or more layers wherein the layers are not joined by a yarn from one layer moving into the other layer so as to connect the layers.

Likewise, the present invention is not concerned with fabrics in which there are not two layers formed from yarn rather than, for example, non-yarn fibre-based materials.

Indeed, the use of a double layered fabric means that the fabric is made (e.g. woven) in a single process, such that there is no need to join separate layers together.

Embodiments of the double layered fabric are breathable and have good drape and handle. In particular, the fabric suitably benefits from not being stiffened by secondary processes which in other fabric structures may be needed to join two materials together. Furthermore, as is discussed in more detail below, embodiments of the invention are effective in repelling molten metal splash and resist heat and flame.

Suitably, the double layered fabric is a double weave. Thus, suitably the yarns are woven together in a single process to form the double layered fabric. An example of a double weave is shown in Figure 1, wherein two layers 18, 20 are held together by yarns 16 from the bottom layer (weave rear) moving up to the top layer (weave front) and then back down again so as to connect or interlock the layers. This is achieved in a single weaving process, suitably by weaving some of the weft picks arid optionally also some of the warp threads from the back layer into the face layer.

Preferably, the weave face is a plain weave. Suitably the weave back is a plain weave.

An advantage of a double weave is that the fabric is woven in a single process, which is more efficient and has lower costs as compared to a process where each fabric layer is manufactured separately and then joined together (e.g. by needle punching or hydrolacing). A further advantage of a fabric woven in a single process is the inherent drapability as the linking yarns are an integral part of the fabric structure, not additional jointing threads or bonding adhesives. The comfort' property is a key advantage for wearers of garments made from this fabric.

The present inventors have also found that the use of a yarn to form both fabric face and fabric back (e.g. weave front and weave rear) provides a strong fabric that is suitable for use in e.g. protective garments for foundry workers. In particular, a fabric face formed from yarn, suitably fluoropolymer yarn, has been found to provide a surface that is adapted to facilitate the shedding of molten metal splashes. Especially in the case of a woven fabric face, the topography of the woven surface is believed to contribute to the efficient "run-off' of molten metal splash.

Whilst a (double) weave is preferred, the fabric can also be a knitted fabric, e.g. a double knit.

Whilst any suitable non-fusible yarn can be used, it is preferred that the non-fusible fibre yarn is an aramid yarn. Suitably, the aramid yarn is a ring spun yarn. Suitably the aramid yarn is a short staple yarn. Preferably the aramid yarn is a ring spun short staple yarn.

Preferably, the aramid yarn comprises meta aramid. Preferably the aramid yarn is a meta aramid yarn. Typically the aramid yarn comprises at least 50% meta aramid (wt% based on weight of the yarn), more typically at least 80% meta aramid and most typically at least 90% meta aramid. A particularly preferred range is 85% to 95% meta aramid, with about 93% especially preferred.

Preferably the aramid yarn comprises para aramid. Preferably the para ararnid content is at least 2% (wt% based on weight of the yarn), more preferably at least 4%. Suitably the para aramid content is no more than 20%, preferably no more than 10%, more preferably no more than 8%. A particularly preferred range is 4% to 8%, with about 5% especially preferred. Preferably the aramid yarn is a meta aramid and para aramid blend.

Suitably, the aramid yarn contains anti stat, preferably in an amount of 1% to 5% (wt% based on weight of the yarn), more preferably 2% to 4% and especially about 2%. An example of a suitable anti stat material is carbon fibre P140.

Indeed in a preferred embodiment, the aramid yarn is a meta aramid, para aramid and anti stat blend. Preferably the blend comprises, suitably consists of, 85% to 95%, meta aramid, 4% to 8% para aramid and 2% to 4% anti stat. Especially preferred is for the aramid yarn to comprise about 93% meta aramid, about 5% para aramid and about 2% anti stat. The use of Aramid yarns is particularly advantageous because they do not have a melting point and do not support combustion and are therefore inherently heat and flame resistant. That is, they do not require chemical treatment to provide flame and heat resistant properties. Chemical treatment is not desirable because it diminishes over time and particularly after washing. This means that such fabrics need replacing regularly. It also means that the wearer of the garment is unsure of whether the fabric is providing the required protection (except in the unfortunate event of an accident) because there is no physical indication of when the garment needs replacing.

Whilst any suitable fluoropolymer yarn can be used, it is preferred that the fluoropolymer yarn is poly(tetrafluoroethylene) (PTFE) yarn.

Suitably, the fluoropolymer yarn is a monofilament or multifilament yarn, preferably a continuous multifilament yarn.

A fluoropolymer yarn of any suitable cross-section can be used. In embodiments, a fibrillated yarn can be used. In other embodiments, a slit film yarn can be used. In other embodiments, a spun yarn can be used.

Twisted or flat (no twist) yarns can be used. In embodiments, the fluoropolymer yarn of the fabric face is flat (no twist) yarn.

Suitably the fabric consists essentially of, preferably consists of, fluoropolymer yarn (suitably PTFE yarn) and non-fusible fibre yarn (suitably aramid yarn).

Preferably, the major component of the fabric face (e.g. weave face) is fluoropolymer yarn. For example, in the case of a double weave fabric, the major component of the warp and weft of the fabric face is fluoropolymer yarn. More preferably at least 95% (wt% based on the weight of the fabric face) of the fabric face is fluoropolymer yarn, more preferably at least 98% and most preferably substantially all (i.e. about 100%) of the fabric face is fluoropolymer yarn.

The metal spatter and heat performance of the fabric is particularly enhanced when the fabric face consists essentially of, preferably consists of (i.e. is 100%) fluoropolymer yarn. Preferably, the fabric face consists essentially of, more preferably is 100% PTFE yarn. Suitably the fabric front is 100% PTFE continuous multifilament yarn.

Suitably, the major component of the fabric back (e.g. weave back) is non-fusible fibre yarn for example, in the case of a double weave fabric, the major component of the warp and weft of the fabric back is non-fusible fibre yarn, more preferably at least 80% (wt% based on the weight of the fabric back), more preferably at least 84%, more preferably at least 88%, and most preferably at least 90% of the fabric back is non-fusible fibre yarn. Typically no more than 98%, preferably no more than 96% and most preferably no more than 94% of the fabric back is non-fusible fibre yarn. An especially preferred amount is about 90.5%. Suitably the remainder of the fabric back is fluoropolymer yarn.

Preferably a minor component of the fabric back is fluoropolymer yarn. More preferably at least 2% (wt% based on the weight of the fabric back), more preferably at least 4%, more preferably at least 6% and most preferably at least 8% of the fabric back is fluoropolymer yarn. Suitably no more than 20%, preferably no more than 16%, more preferably no more than 13%, more preferably no more than 12% and most preferably no more than 10% of the fabric back is fluoropolymer yarn. A particularly preferred range is 4% to 13%, more preferably 6% to 10%, especially about 9.5%. Suitably the remainder of the fabric back is non-fusible yarn.

It is especially preferred that the fabric back consists essentially of, preferably consists of, non-fusible yarn and fluoropolymer yarn. Preferably they are present in the range 88%-94% non-fusible yarn and 6% tol2% fluoropolymer yarn.

As discussed above, a characteristic of a double layered fabric is the interconnecting or interlocking of yarn from the fabric back with the fabric face at predetermined points on the fabric, to form a single fabric. It is preferred that fluoropolymer yarn from the fabric back interconnects or interlocks with the fabric face. That is, preferably the fluoropolymer yarn of the fabric back interlocks in the fabric face at selected points. Thus, suitably a binding thread connects the two layers of the fabric and the binding thread is fluoropolymer yarn.

For example, in the case of a double weave this can be achieved by providing the weave back with at least some picks, which are fluropolymer yarn, which picks are interwoven not only with the warp of the weave back but also, at selected points on the fabric, with the warp of the weave face.

It is particularly preferred that the major component of the fabric face is fluoropolymer yarn, the major component of the fabric back is non-fusible fibre yarn, and a minor component of the fabric back is fluoropolymer yarn; and the fluoropolymer yarn from the fabric back interlocks in the fabric face at selected points. Thus, suitably, the fluoropolymer yarn from the fabric back interlaces on the fabric face at selected points.

In embodiments the double layered fabric is a double weave and the fluoropolymer yarn from the weave back is woven into (interweaves) the weave face at selected points. Suitably this is achieved by a fluoropolymer yarn weft of the weave back passing up to the face weave. In this way, the fluoropolymer yarn weave face is connected to the non-fusible fibre yarn weave back with a fluoropotymer yarn.

Suitably this permits the weave face to be not only homogenous in the sense of having a regular "normal" woven face, but also to be substantially free of the non-fusible fibre yarn (e.g. to be 100% PTFE yarn). Indeed, in embodiments where the weave face consists essentially of fluoropolymer yarn, by providing fluoropolymer yarn on the weave back and moving that yarn to the weave face, the only yarn that is visible (and hence in use exposed to molten metal splash) on the weave face is fluoropolymer yarn.

Furthermore, by providing a fluoropolymer yarn in the weave back which is woven into the weave face, the double weave can have a fluoropolymer weave face that has a closed surface and has a low coefficient of friction. Suitably, there are no holes or areas on the fabric face that molten metal can penetrate. Suitably when molten metal hits the fabric, it rolls or slides away from the impact site, thus not damaging the garment. The weave back of non-fusible fibre yarn provides additional protection from heat and also provides secondary ("back-up") physical protection should a splash of molten metal hit the fabric where there is a crease and not move away from the impact site. In such a situation, the molten metal will char the fluoropolymer but not burn through the "back-up" protection.

Preferably the fabric face is flat. Preferably the fabric face does not have any creases, bumps or raised threads when laid on a flat rigid surface. It is preferred that the fabric face is smooth, that is, when draped, there are no creases, bumps or raised threads on the surface.

Suitably, the fabric back is puckered. Preferably, the fabric comprises air pockets or "pillows". It is preferred that the air pockets are formed between the fabric back and the fabric face. An advantage of this arrangement is that the thermal conduction of the fabric can be reduced. A further advantage is that the puckered or pillowed" structure can minimise the contact surface area between the fabric and the skin of the wearer, thus further improving the heat resistance of the fabric and the comfort for the user. In embodiments, the puckered fabric back allows the fluoropolymer fabric face to remain flat even if the fabric back shrinks. For example, in the case of a fabric back comprising aramid, which will shrink to some extent when laundered, the provision of a puckered fabric back (i.e. comprising "excess" fabric in the fabric back) will permit shrinkage of the aramid whilst maintaining the flat fluoropolymer (e.g. PTFE) fabric face. In this way, a garment comprising the fabric can continue to provide a fabric face that is effective at shedding molten metal splash.

In preferred embodiments, the fabric weight is a maximum of 650 g/m2, preferably 600 gIm2. A suitable minimum weight is 350 g/m2, preferably 450g/m2 and most preferably 500 g/m2. Preferably the fabric weight is in the range of 350 -650 g/m2, more preferably 450 -650 g/m2, and most preferably 500 -600 g/m2. These fabric weights are particularly advantageous because they permit production of a light-weight garment. Such garments are particularly comfortable for the user, and also more practical for carrying out heavy work in hot environments.

Suitably the warp and weft densities of the fabric face and fabric back are selected independently. They can be the same or different. Preferably the warp density of the fabric face is substantially the same as the warp density of the fabric back.

The following discussion of warp and weft densities applies independently to each of the fabric face and the fabric back.

Preferably, the minimum weft density is 25 threads/cm, more preferably 30 threads/cm, and most preferably 32 threads/cm. A suitable maximum weft density is threads/cm, preferably 50 threads/cm, more preferably 45 threads/cm and most preferably 40 threads/cm. Suitably the weft density is in the range 25-60 threads/cm, more preferably 30-50 threads/cm and most preferably 30 -45 threads/cm. A particularly preferred value is about 35 threads/cm.

Suitably, the minimum warp density is 35 threads/cm, more preferably 40 threads/cm, more preferably 43 threads/cm and most preferably 45 threads/cm. A suitable maximum warp density is 65 threads/cm, preferably 60 threads/cm, more preferably 55 threads/cm and most preferably 50 threads/cm. Preferably the warp density is in the range 35-65 threads/cm, more preferably 40 -60 threads/cm, and most preferably 45 -55 threads/cm. A particularly preferred value is about 48 threads/cm, Preferably the weft and warp density create a fabric face with a closed surface.

These weft and warp densities are particularly advantageous because they provide a tight" weave, which further reduces flame spread and improves mechanical characteristics such as tear strength, tensile strength and abrasion. The creation of a closed surface is further advantageous because it prevents molten metal spatter from intruding through the weave face.

Preferably, the fluoropolymer yarn is at least 300 denier yarn. A suitable maximum denier is a 1500 denier yarn, preferably 1300 denier yarn. Preferably the fluoropolymer yarn is selected from the ranges 300 -600 denier yarn and 1000 to 1300 denier. The most preferred is 300 -600 denier, with about 400 denier especially preferred.

In embodiments, more than one weight (denier) of fluoropolymer yarn is used.

Preferably the denier of at least some of the fluoropolymer yarn used in the weave back is less than that of the fluoropolymer yarn in the weave face. In particular, the weft fluoropolymer yarn of the weave back can be lighter (finer denier) than the weft fluoropolymer yarn of the weave face. For example, the weft fluoropolymer yarn of the weave face is in the range 1000 to 1500 denier (e.g. about 1200 denier), whilst the weft fluoropolymer yarn of the weave back is in the range 300 to 600 denier (e.g. about 400 denier). An advantage of using a lighter (finer denier) fluoropolymer yarn in the weave back is that it minimises the disturbance of the fabric face when the fluoropolymer yarn moves to the fabric face. In particular, it is preferred that in embodiments were a binding thread connects the two layers of the fabric, the binding thread is fluoropolymer yarn in the range 300 to 600 denier.

Generally, the denier of the warp fluoropolymer yarn is the same for the weave face and weave back (being typically 300 to 600 denier, e.g. about 400 denier).

Suitably the non-fusible fibre yarn is aramid yarn and is selected from ring spun short staple aramid yarn in the range 40I2Nm to 80f2Nm, preferably 50/2Nm to 70/2Nm. A value of about 60/2Nm is especially preferred. Suitably the warp aramid yarn and weft aramid yarn of the fabric back are selected from 50/2Nm to 70/2Nm. Preferably they are both the same.

In preferred embodiments the warp aramid yarn of the fabric back is about 60/2Nrn ring spun short staple aramid yarn and the weft aramid yarn is about 60/2Nm ring spun short staple aramid yarn.

In a particularly preferred embodiment, PTFE yarn and aramid yarn are woven into a double weave, wherein the weave face is 100% PTFE yarn, which creates a smooth closed surface with low friction between itself and molten metal, so that molten metal splashes can easily slide or roll away from the site of impact. The weave back is at least 80% aramid yarn, which provides heat and flame resistance and additional protection from metal spatter, should it char through the PTFE yarn weave face.

In embodiments, for example where the fabric is part of a garment, the double layered fabric may be provided in combination with one or more other materials or textiles. For example, a garment may comprise a plurality of layers, of which one is the double layered fabric.

Suitably the double layered fabric passes the EN ISO 11611.2007 standard. Suitably the double layered fabric passes the EN ISO 11612.2008 standard. In a preferred embodiment, the double layered fabric passes the EN ISO 11612:2008 and the EN ISO 11611:2007 standards.

In a further aspect, the present invention provides a fabric comprising a fluoropolymer yarn and a non-fusible fibre yarn, wherein the yarns form a double layered fabric, and wherein the double layered fabric passes the EN ISO 11611:2007 standard. The optional and preferred features of the first aspect suitably also apply to this aspect.

In a further aspect the present invention provides a fabric comprising a fluoropolymer yarn and a non-fusible fibre yarn wherein the yarns form a double layered fabric, and wherein the double layered fabric passes the EN ISO 11612:2008 standard. The optional and preferred features of the first aspect suitably also apply to this aspect.

In a further aspect the present invention provides a personal protective garment comprising a fluoropolymer yarn and a non-fusible fibre yarn wherein the yarns form a double layer garment. Preferably, the personal protective garment comprises the fabric of the first aspect. The optional and preferred features of the first aspect suitably also apply to this aspect. Personal protective garments include, but are not limited to, jackets, aprons, trousers, hoods, caps, coats, gloves, shoes, overshoes, coveralls and boiler suits.

In a further aspect the present invention provides a protective screen comprising a fluoropolymer yarn and a non-fusible fibre yarn wherein the yarns form a double layer screen. Preferably, the protective screen comprises the fabric of the first aspect.

The optional and preferred features of the first aspect suitably also apply to this aspect. Protective screens include, but are not limited to, curtains (e.g. for screening off a work area) and portable stand-alone boards (e.g. for screening a work area).

In a further aspect the present invention provides a protective cover comprising a fluoropolymer yarn and a non-fusible fibre yarn wherein the yarns form a double layer cover. Preferably, the protective cover is made from the fabric of the first aspect. The optional and preferred features of the first aspect suitably also apply to this aspect. -10-

Protective covers include, but are not limited to computer covers and covers for electrical appliances.

In a further aspect the present invention provides a method for manufacturing a fabric comprising a fluoropolymer yarn and non-fusible fibre yarn, wherein the yarns are processed to form a double layered fabric, suitably a double weave. The optional and preferred features of the first aspect suitably also apply to this aspect.

In one embodiment, the method of making the fabric is by weaving a double weave, wherein the weave face is 100% fluoropolymer yarn (preferably PTFE yarn) and the major component of the weave back is non-fusible fibre yarn (preferably aramid yarn). Preferably, there is some fluoropolymer yarn in the weave back. Suitably, the fluoropolymer yarn from the weave back interlocks on the weave face at selected points. In a preferred embodiment, the weave back comprises fluoropolymer yarn weft picks and the fluoropolymer weft picks from the weave back are woven into the weave face. It is particularly preferred that the fluoropolymer weft picks move to the weave face (i.e. is woven into the weave face) at regular intervals. That is, preferably the fluoropolymer weft pick is a binding thread.

In a further aspect the present invention provides a method of making a double weave comprising a fluoropolymer yarn and non-fusible fibre yarn, wherein the non-fusible fibre yarn and fluoropolymer yarn are differentially shrunk. Preferably, the double weave has a weave face of 100% fluoropolymer yarn (suitably PTFE yarn) and the major component of the weave back is non-fusible fibre yarn (suitably aramid yarn). Suitably, the weave back is puckered as a result of the differential shrinkage of the fluoropolymer yarn and non-fusible fibre yarn. Preferably the weave face is flat. Suitably the step of shrinking the fabric so that it undergoes differential shrinkage includes forming a flat fabric face.

In a preferred embodiment, the fluoropolymer yarn in the weave back forms a regular grid pattern. In such a preferred embodiment, the differential shrinkage produces regular pockets of air ("pillows") between the weave face and the weave back.

Indeed, in embodiments, differential shrinkage produces puckering of the weave back as discussed above. Suitably, the differential shrinkage of the double weave results in a final weft density of 25 -60 threads/cm. Preferably the final warp density is 35 -65 threads/cm.

In a further aspect the present invention provides a use of fluoropolymer yarn and non-fusible fibre yarn to form a double layered fabric. Suitably, the double layered fabric is a double weave.

Any one or more of the aspects of the present invention may be combined with any one or more of the other aspects of the present invention. Similarly, any one or more of the features and optional features of any of the aspects may be applied to any one of the other aspects. Thus, the discussion herein of optional and preferred features may apply to some or all of the aspects. In particular, optional and preferred features relating to the fabric, for example the nature of the yarn, including the material and weight (denier), as well as the structure of the fabric (e.g. double weave, yarn density) apply to all of the other aspects. Furthermore, optional and preferred features associated with a method or use may also apply to a product, in particular a protective garment, and vice versa.

Brief Description Of The Drawincis

Embodiments of the invention are described below, by way of example only, with respect to the accompanying drawings, in which: Figure 1 schematically illustrates the cross section of a double weave.

Detailed Description Of Embodiments

In this application, "double layered fabric" means a single fabric which has two layers, the layers being interconnected by a yarn (e.g. warp or weft "binding thread") that is constituent part of one of the layers and moves to the other layer, thereby holding the two layers together. Such a single fabric is fabricated (e.g. woven) in a single step or process. An example of a double layered fabric is a double weave, whereby the two layers are formed (and joined) in a single weaving process.

In this application, "double weave" means a woven textile in which two or more sets of warps are interconnected (typically by a weft pick moving from the weave rear to the weave front) to form a two-layered cloth. The two layers are woven in the loom at the same time. A double weave is also known as a double cloth and is an example of a double layered fabric. An example of a double weave is shown in Figure 1. The single fabric unit has two layers: upper layer 18 and lower layer 20. Weft pick 12 weaves through warp thread 10 of lower layer 20, until at a predetermined point 16 the weft pick 12 moves to upper layer 18, and weaves through the warp threads of -12-upper layer 18. After weaving through a predetermined number of yarn threads in the upper layer, the weft pick 12 returns to lower layer 20. The reverse of this occurs for weft pick 14, in that it weaves along the warp of upper layer 18, until at a specific point it moves to lower layer 20, and weaves along the warp of layer 20, returning at a specific point to layer 18. A pattern of these weft pick movements can be created across the weave.

In this application, "fabric face" refers to the upper layer of a double layered fabric, being the side of the fabric that in use would be directly exposed to molten metal. For example, in one embodiment this would be a 100% PTFE yarn layer. In the preferred embodiments where the fabric is a double weave, the fabric face is referred to as the "weave face" or "weave front".

In this application, "fabric back" refers to the bottom or lower layer of the double layered fabric, being the side of the fabric that in use would not be directly exposed to molten metal. For example, when the fabric forms part of a personal protective garment, it is the side closest to the skin of the user. In the preferred embodiments where the fabric is a double weave, the fabric back is referred to as the "weave back" or "weave rear".

In this application, "fluoropolymer" refers to polymers generally known as fluorinated polymers, with fluorinated olefinic polymers being preferred, for example polytetrafluoroethylene (PTFE).

In this application, "non-fusible fibre yarn" means a yarn manufactured from fibres which will not leave a molten trail on a hot surface at 300°C. These yarns therefore have good heat and flame resistance. An example of a non-fusible yarn is an aramid yarn. Aramid yarns do not support combustion and do not have a melting point.

As the skilled reader will recognise, the yarns disclosed herein are heat stable such that shrinkage and loss of mechanical properties is limited after exposure to high temperatures and/or flames for a short time (of around 3 to 4 seconds).

In this application, "puckered" refers to a puffed, crinkled, corrugated or blistered effect, created, for instance, by a process such as differential shrinkage.

In this application, "differential shrinkage" refers to a process wherein two different yarns are combined in a single fabric which is then subjected to shrinkage whereby one yarn shrinks by a greater amount than the other yarn.

In this application, reference to "flat" in the context of a fabric means a fabric that when laid on a rigid, smooth, flat surface is free from any bumps, creases or raised portions of thread. Generally this means that there is nothing in the construction of the fabric that encourages part of the surface to be raised compared to the rest of the surface.

In this application, "closed surface" means a fabric surface where only the yarns of that surface or layer can be seen by visual inspection, rather than any yarns of an underlying layer. For example, in the case of a double weave, a closed surface weave face means that the fabric back cannot be seen through the weave face.

In the following example, aramid yarn was Nomex® 93 / 5 / 2 (from Aramex®) and PTFE yarn was obtained from Toray Fluorofibers (America).

A double layered fabric was made using multifilament unbleached PTFE yarn and ring spun short staple aramid yarn. The fabric was woven using 2 warp yarns and 3 weft yarns to form a double weave.

One of the warp yarns was 60/2 Nm ring spun short staple meta aramid, para aramid, anti stat blend yarn (Nomex®93 / 5 / 2 with carbon P140 anti-stat, from Aramex®), and the other one is 400 den multifilament unbleached PTFE twisted 200 tpm yarn.

The first of the weft yarns was 1200 den multifilament PTFE (which can be bleached or unbleached) flat (no twist) yarn. The second of the weft yarns was 400 den multifilament PTFE (which can be bleached or unbleached) flat (no twist) yarn. The third weft yarn was the same 60/2 Nm ring spun short staple aramid as used for the warp yarn.

The weave face was formed from the 400 den PTFE warp yarn and 1200 den FTPE weft yarn. This means that the weave face had only one type of warp yarn and one type of weft yarn, both of which were PTFE.

-14 -The weave back had a more complicated structure.

Two types of warp yarn were used: the 60/2 Nm aramid yarn and the 400 den PTFE yarn. The aramid yarn was the major warp component and the PTFE yarn the minor warp component. The aramid and PTFE warp yarns were arranged to provide a repeating pattern of one PTFE warp thread and fifteen aramid warp threads. This created a warp pattern of "blocks" of aramid warp ends interspaced with single PTFE warp ends.

Similarly, two types of weft yarn were used: the 60/2 Nm aramid yarn and the 400 den PTFE yarn. The aramid yarn was the major weft component and the PTFE yarn the minor weft component. The aramid and PTFE weft yarns were woven into the warp to provide a repeating weft pattern of one PTFE weft and fifteen aramid weft picks.

The (minor component) PTFE warp threads and weft picks of the weave back formed a matrix check. Visual inspection of the weave back showed a rectangular grid of PTFE yarn, wherein each rectangle comprised an outline of PTFE yarn enclosing or surrounding an aramid yarn centre.

Importantly, the PTFE weft picks of the weave back were, at specific points, moved to the weave face, to link the weave face and weave back together to from a single fibre unit.

In this way, weft threads form the PTFE matrix check on the weave back were moved to the weave face to create a 100% PTFE yarn weave face. Thus, the interlocking threads (binding threads) which show through on the weave face were PTFE, just like the rest of the weave face (weave face warp and weft being 400 den PTFE yarn and 1200 den PTFE yarn).

In other words, the face of the weave had only PTFE warp and weft yarns. In weaving the fabric, the PTFE weft yarns from the back of the weave were woven onto the face of the weave. That is, when weaving the PTFE weft yarn on the back of the weave, it not only passed under the warp yarn of the weave back, but over the warp yarn of the weave face. This process linked the face and back of the weave together in the weaving process to provide a single fabric unit. In this way, the PTFE weft yarn is a binding thread which connects the two layers. -15-

This combination of yarns and weave pattern resulted in a single fabric with an overall composition of (wt% based on weight of the fabric) 67% PTFE, 30% meta aramid, 2% para aramid and 1% anti-stat.

Once woven, the fabric was then finished using standard processes known in the art.

The finishing processes included scouring, drying and setting the weave.

In this particular example, the weave was set such that the PTFE yarn shrunk by approximately 11-12% and the aramid yarn shrunk by approximately 3%. This caused puckering of the back of the weave. This puckering was such that pillows" or cushions" of air were formed between the weave face and the weave back. This arose because of the matrix check (rectangular grid) of PTFE yarn on the weave back: the PTFE outline or border of each rectangular "check" shrunk considerably more than the "inner" aramid, causing puckering.

After the finishing process, the finished warp density was 48 threads/cm, the finished weft density was 35 threads/cm and the total finished weight was 600 g/m2.

The above process created a double weave having a weave face that was 100% PTFE yarn; and a weave back that was primarily aramid yarn, but had a rectangular grid of PTFE weft and warp threads. This method of manufacture and structure of the fabric created a flat and closed surface weave face, with no holes or areas in which metal spatter can easily penetrate the PTFE weave face, and no creases or bumps to prevent the metal spatter from rolling or sliding away from the site of impact. The back of the weave however was puckered, thereby creating cushions of air between the weave face and weave back, caused by the grid of PTFE yarn and the interlocking of the back PTFE warp and weft yarns to the face of the weave.

In testing it has been found that when molten metal spatters hit the PTFE surface, they roll or slide away from the site of impact, due to the low coefficient of friction between molten metal and PTFE, and the closed homogeneous surface. This then means the molten metal does not stay at the site of impact, which would result in an increase in temperature at the impact site and allow the molten metal to char through the front layer of the fabric. This has a considerable industrial and commercial benefit in that the garment is not damaged when hit by molten metal and therefore maintains a high level of protection for the user and also does not need replacing.

-16 -The use of an aramid yarn provides the advantage of improved heat and flame resistance when compared to the use of PTFE on its own. It also provides increased protection for the user, since it offers an additional protective layer. For instance, should molten metal hit the PTFE face, and if the droplet was sufficiently large and was caught in a crease so that it could not roll or slide away from the impact site, it may char through the PTFE yarn. However, it would then reach the aramid back of the weave, which would prevent it from burning through to the user's skin.

The air "pillows" between the PTFE front and weave back, created from puckering due to differential shrinkage of the PTFE and aramid yarn, have the advantage of decreasing the thermal conduction of the fabric. In addition, the puckering also reduces contact area of the fabric with the skin, thus improving comfort for the user.

Furthermore, the puckering can assist in maintaining a flat PTFE weave front, particularly after washing/laundering of the fabric.

The use of multifitament unbleached PTFE yarn provides an additional durability, since multifilament yarns are particularly durable yarns.

The combination of yarns to produce a weave is advantageous since the two textiles (fluoropolymer and non-fusible fibre yarn) are combined together in a single process.

This creates a cost effective method of production. The use of the weave also means that the fabric is very light weight, which has advantages for user comfort.

The resulting double weave construction also produces a product that is breathable, and drapes well, so is easy to use in garment, cover or screen manufacture. Also, the final "tight" weave reduces flame spread and improves mechanical characteristics of the fabric such as tensile strength, tear strength and abrasion.

The fabric was tested for mechanical properties, flame and heat resistance, and molten metal splash resistance as well as electrical resistance in accordance with EN ISO 11611:2007 and EN ISO 11612:2008. The fabric not only passed the tests but substantially exceeded the performance requirements of many of the tests. In particular, the performance in the molten metal (aluminium and iron) tests exceeded the highest thresholds, being "D3" for molten aluminium and "E3" for molten iron.

The fabric not only passed, but showed excellent performance in all EN ISO 11611:2007 tests. The tensile and tear strength were considerably higher than -17-required by the standard. The fabric also showed exceptional performance in the flame spread tests, with no after flame or after glow, which exceeds the performance required by the standard.

In the impact spatter tests, the highest class of fabric is only required to withstand 25 drops, but this fabric could withstand considerably more than that. The heat transfer was also better than the standard requires. Also, impressively, the fabric had an electrical resistance much higher than that required by the standard.

The fabric passed the following parts of the EN ISO 11611:2007 standard: -Tensile strength [ISO 13934-1: 1999] -pass class 1 and 2 -Tear strength [ISO 13937-2: 2000] -pass class 1 and 2 -Dimensional change [ISO 5077: 2007] -pass Flame spread -Face ignition (code letter Al) [ISO 15025:2000 Procedure A] -pass Al class 1 and 2 -Flame spread -Edge ignition (code letter A2) [ISO 15025:2000 Procedure B (folded edge)] -pass A2 class 1 and 2 -Impact of spatter [ISO 9150: 19881-pass class 1 and 2 -Heat transfer (radiation) [ISO 6942:2002; Method B at 20 kW/m2] -pass class 1 and 2 -Electrical resistance [EN 1149-2: 1997 at 85± 5% r.h.] -pass class 1 and 2 -pH-value [ISO 3071:2005] -pass class I and 2 The fabric also passed and performed highly to EN ISO 11612:2008. Again, it exceeded the tensile and tear strength required, and there was no flame spread or after glow in the limited flame spread tests. The fabric passed the heat resistance test, convective heat test, and the radiant heat test. The performance of the fabric in the metal spatter tests was to the highest possible level (D3 and E3).

The fabric passed the following parts of the EN ISO 11612:2008 standard: -Heat resistance (at 180°C and 260°C) [ISO 17493: 2000 at 180°C] -pass -Limited flame spread -Face ignition (Al) (tested "as received") [ISO 15025: 2000 Procedure A] -pass Al -Limited flame spread -Face ignition (Al) (tested after pre-treatment) [ISO 15025: 2000 Procedure A] -pass Al -Limited flame spread -Edge ignition (A2) (tested "as received") [ISO 15025: 2000 Procedure B (folded edge)] -pass A2 -Limited flame spread -Edge ignition (A2) (tested after pre-treatment) [ISO 15025: 2000 Procedure B (folded edge)] -pass A2 -Dimensional change [ISO 5077: 2007] -pass -Tensile strength [ISO 13934-1:1999] -pass -Tear strength [ISO 13937-2: 2000] -pass -pH value [ISO 3071: 2005] -pass -Convective heat (Code letter B) [ISO 9151: 1995] -pass level B2 -Radiant heat (Code letter C) [ISO 6942:2002 Method B at 20kW/rn2] -pass level Cl and C2 -Molten aluminium splash (Code letter D) [ISO 9185: 2007] -pass level 03 -Molten iron splash (Code letter E) [ISO 9185: 2007] -pass level E3 The fabric also passed electric arc test EN 61482-1-2: 2007 Box Test to Class 2.

The fabric passed the following parts of EN ISO 14116: 2008 Thermal Performance -Limited flame spread index -level 3 The fabric passed the following parts of EN 1149-5: 2008: Induction Decay Test -Conductive thread spacing -PASS -Shielding factor & half decay time -PASS -19-

Claims

Claims 1. A fabric comprising a fluoropolymer yarn and a non-fusible fibre yarn, wherein the yarns form a double layered fabric.
2. A fabric according to claim 1, wherein the double layered fabric is a double weave.
3. A fabric according to claim I or claim 2, wherein the non-fusible fibre yarn is araniid yarn.
4. A fabric according to any one of claims I to 3, wherein the fluoropolymer yarn is PTFE yarn.
5. A fabric according to any one of claims 1 to 4, wherein the major component of the fabric face is fluoropolymer yarn, the major component of the fabric back is non-fusible fibre yarn, and a minor component of the fabric back is fluoropolymer yarn; and wherein fluoropolymer yarn from the fabric back is interwoven in the fabric face.
6. A fabric according to any one of claims 1 to 5, wherein the fabric face consists of fluoropolymer yarn.
7. A fabric according to any one of claims 1 to 6, wherein the fabric face has a closed surface.
8. A fabric according to any one of claims 1 to 7, wherein the fabric back is puckered and the fabric face is flat.
9. A fabric according to any one of claims I to 8, wherein the fabric weight is in the range 350 to 650 g/m2.
10. A fabric according to any one of claims 1 to 9, wherein the double layered fabric is a double weave and the weft density is in the range 25 to 60 threads/cm.
11. A fabric according to any one of claims 1 to 10, wherein the double layered fabric is a double weave and the warp density is in the range 35 to 65 threads/cm.

-20 -
12. A fabric according to any one of claims I to 11, wherein the fluoropolymer yarn is PTFE yarn with a denier in the range 300 tol 300 denier.
13. A fabric according to any one of claims ito 12, wherein the fabric passes the EN ISO 11612:2008 and the EN ISO 11611:2007 standards
14. A personal protective garment comprising the fabric of any one of claims 1 to 13.
15. A method of making a double weave, where the weave face is 100% fluoropolymer yarn and the major component of the yarn of the weave back is non-fusible fibre yarn.
16. A method according to claim 15, wherein the method includes the step of shrinking the fabric so that it undergoes differential shrinkage to produce a puckered weave back.