The present invention relates to heat and moisture management fabric for use in the manufacture of garments.

In order to maintain an even and comfortable internal and external temperature the human body employs a number of strategies such as increasing or decreasing heart rate, shivering and/or perspiring. There have been many and varied attempts to make clothes which assist the body in keeping dry at a constant temperature of 25°C with 60% relative humidity. Previously proposed clothing has had limited success due to the dramatic changes in activity from sitting to running, from walking to climbing, from day to night, and from winter to summer. The rate of perspiration of the human body can vary from 500 cc per hour to 10,000 cc per hour and once the water vapour turns to liquid and is absorbed by normal clothing the insulation properties of the material are lost and the wearer feels uncomfortable. A second major problem with the human body is that heat and perspiration are generated under the arms, around the chest and on the upper back, it is therefore important to design clothing systems where air is allowed to circulate from hot parts to cooler parts of the body. It is an aim of the present invention to provide a fabric designed to bring about the dissipation of heat and moisture in order to avoid discomfort to the wearer particularly when the wearer is dressed in stab- or bullet-proof vests, wet suits or diving gear by absorbing free water through a membrane that touches the skin which remains relatively dry. It is further aim of the present invention to conduct heat away from the hotter parts of the body to the cooler parts of the body.

Accordingly the present invention is directed to a fabric comprising two different fibres and/or yarns, a first fibre and/or yarn consisting substantially of a non absorbent fibre and/or yarn with an ability to move moisture via its wicking properties and second fibre and/or yarn comprising of a super- absorbent fibre and/or yarn capable of absorbing water.

The advantage of the present invention is that a super- absorbent fibre is capable of absorbing up to 100 times its own weight in water. Normal super-absorbent fibres and/or yarns are unacceptable in apparel as once they have absorbed water through contact with the skin they form a gel which can migrate onto the skin. The present invention provides the advantage that by using a wicking fibre to transfer water from the skin to the superabsorbent fibre there is no need for the superabsorbent fibre to be in contact with the skin and therefore a reduced chance of any migration of the gel. The use of a super-absorbent fibre in clothing provides the advantage that on absorption of water the moisture there can be up to a 6 °C drop in temperature caused by the absorption of the water. This provides extra cooling from the use of the fabric . In a preferred embodiment the super-absorbent fibre is enclosed via twisting methods, chainetting or yarn covering techniques including braiding or over wrapping with non-woven structures. This provides the advantage that it further improves the prevention of the migration of gel onto the human skin.

Advantageously the fabric has an outer layer or membrane constructed from the first fibre or yarn or alternatively from fibres capable of wicking moisture that is sufficiently tightly constructed to prevent a super-absorbent fibre from migrating through it.

In a preferred embodiment a highly conductive fibre or yarn can be included in the compound yarn as a core material or within the membrane in order to transfer heat away from the hot areas of the body to the cooler areas. This provides the advantage of allowing transfer of the heat from the human torso to other parts of the clothing thereby increasing the cooling effect described above.

In a preferred embodiment the fabric is constructed of a fine yarn warp and part fine yarn and part compound yarn weft to produce a rib structure which would allow water vapour and heat to be channelled away from the hot parts to the cool parts .

Advantageously, the rib structure can be manufactured by weaving warp knitting weft knitting or non-woven structure or slither knitted fabric. The advantage of these techniques is again the channelling of heat and moisture away from hot areas to the cool areas of the fabric.

The cooling effect of using super-absorbent fibres works without the necessity of adding high thermal conducting material to the fabric. It should be noted that high thermal conducting materials will work without using the super- absorbent fibres but the insulation property of the clothing will be lost once it becomes wet which is its main function. The super-absorbent materials control the moisture by chemically locking it away.

The use of heat and moisture management fabric described above is especially useful in:

a) conveying heat and moisture from beneath bullet and stab resistant vests;

b) sportswear, preventing extremes of temperature and loss of insulation when fabrics become wet, a shell-suit would be a perfect example;

c) a knitted version for sports socks;

d) for use in climbing jackets and fell-walking gear; and e) for use in a wet suit or diving gear where it is difficult to balance the hot and wet areas with dryer and cooler areas of the body.

Preferably the fabric is laminated with fine pour membranes on both back and face of the fabric. This provides the advantage that the unprotected super absorbent fibres or yarns may be rendered washable.

In a preferred embodiment the fine core membrane is laminated to the fabric contained in the super absorbent fibre in areas of fibres containing non-absorbent material. This provides the advantage that no delamination occurs once the fabric is washed or wetted due to the super absorbent materials weak bonding . Advantageously, the fabric is constructed of slither knit and slither loop knit fabrics to allow maximum absorption. This provides the advantage that the maximum absorption of the water by the super absorbent fibres. In a preferred embodiment the fabric comprises of a range of fibres having specific properties and constructions to bring dissipation of heat and moisture in order to avoid discomfort to the wearer particularly when the wearer is dressed in a stab or bullet proof vest, wetsuit or diving gear.

Advantageously the fabric may be of flat or ribbed construction .

In the preferred embodiment the construction is ribbed and the ribs are either in the warp or the weft direction.

The fabric can be constructed from two dissimilar yarns. Preferably, the first yarn would be a fine yarn typically 2/30 worsted count (2/30 tex) made from a cellulose or polyester material or a mixture of both which would assist in wicking away moisture from points of high saturation to dryer areas of the fabric, and the second yarn could be a twisted yarn or an overwrapped non-woven fabric yarn. One of the preferred yarn constructions is a section of non-woven fabric a few centimetres wide which is guided in such a way as to fold over a number of yarns one of which will be swellable super absorbent materials, this folded tape is then bound around by strong fine retaining yarns. Once the super absorbent yarn becomes wet at any point its insulation is lost and it begins to conduct hear away from hot wet places in the fabric. The measured temperature drop from dry to wet is 6° C.

A washable super absorbent yarn according to the present invention may be woven into a fabric for use as, for example, an under vest.

A further aspect of the present invention is directed to a fabric comprising the weaving of uncovered super absorbent yarns together with normal polyester spun yarns in such a way as to create areas of swellable and areas of non-swellable yarn. The woven fabric comprising two yarns would then be laminated on both sides with a non-woven membrane of sufficiently fine pores to prevent loss of super absorbent materials during washing. Experiments have shown that it is not possible to stick a membrane on to a swellable yarn because once the super absorbent fibre swells it loses all its strength and the fabric delaminates. It is therefore desirable to have areas in a fabric where there is no super absorbent fibre but simply 100% polyester or similar yarn on which to obtain good adhesion. This fabric weighs 250 - 300 g/m ² whereas the other fabrics weigh 600 g/m ² . Fabric weights can be adjusted according to the desired results and picks per centimetre.

A further fabric would be a loop sliver knit construction which could be made in a number of different constructions. The new fabrics described above use fine pore fabrics capable of retaining the gel of a super absorbent fibre when wet especially during a washing cycle. In one example of a woven structure the super absorbent fibre yarn is enclosed in a fine pore membrane woven together with other yarns and then the same fine pore membrane is laminated to the face and back of the fabric so that the super absorbent fibre is doubly protected . Lighter constructions use uncovered super absorbent fibre yarns which, for moisture transfer purposes, are combined with wicking yarns during weaving and subsequently laminated back and face with a fine gel retaining fabric or membrane to maintain super absorbent properties after multiple wash cycles .

Super absorbent fibre can be restricted in its ability to swell by any sort of pressure or restriction of space in which to swell and during yarn manufacture twist or wrapper yarns bind super absorbent fibre together with other fibres into the yarn structure. The twist or wrapper yarn inevitably constrains swelling. The density of needling when producing a non-woven product has the same effect as twist in yarn spinning. The denser a fabric is needled the more constrained a super absorbent fibre is in trying to swell. Unlike other fabrics a sliver knitted construction gives more room for the super absorbent fibre to swell. Either less super absorbent fibre needs to be used to give the same absorbency as a woven fabric or the same quantity of super absorbent fibre will give higher absorbency or a more stable lower absorbing fibre could be used to give the same result. A preferred construction of a fabric according to the present invention may consist of two yarns, a compound yarn and a yarn comprising a low moisture absorbing fibre such as polyester. The compound yarn may be manufactured using a tape typically of fine non-woven construction slit to 60mm in width, which is fed through an orifice together with a super-absorbent yarn and a wicking yarn in such a way as to enclose the two yarns which are approximately 1mm in diameter by the 60mm tape, which is then held in position by overwrapping it with fine continuous filament yarns.

The function of the tape is to contain the super-absorbent yarn which, on swelling, may break down and parts of the fibre may be lost. The tape or membrane may have a pore size small enough to contain the vast majority of any super-absorbent fibres or molecules within the enclosing tape. The preferred tape typically has a pore size of 20 micron. Super-absorbent yarns and fibres and powders are good at absorbing water and holding on to it and therefore poor at wicking or transporting water from a saturated to a dry area which is why a non-absorbing wicking yarn is introduced into the compound yarn. A wicking yarn is most effective if it has little or no moisture regain, examples of which may be polyester, polypropylene, glass, carbon, Kevlar ®, nylon and others. The wicking yarn works by capillary attraction where the water is drawn along the fine capillaries formed by the fibre bundles within yarns and this capillary effect is at its best when the fibres making up the yarn do not absorb water. When the compound yarn is measured for the rate of conductivity of water along its length from a point of saturation towards a dry area the rate is 6 cm per minute. As the compound yarn becomes saturated its temperature drops at 50% absorbency. The temperature difference between the fabric and air at 20° C and 65RM is 2° C at 100% absorbency. The differential increases to 4° C. if one thermocouple is held between thumb and finger at 30° C and one thermocouple is held onto a super-absorbent yarn at 100% absorbency then the difference is 12° C. If one thermocouple is held under the armpit while the other thermocouple is on the super-absorbent at 100% saturation, the temperature difference between the two is 16° C. There is no doubt that as a super-absorbent fabric or yarn becomes wetter it not only feels cooler it is measurably cooler but what the temperature differential between any part of the body and the super-absorbent fabric is infinitely variable and will not only vary by differential body temperatures and fabric moisture content but also by the external air temperature and relative humidity, nonetheless the super-absorbent fabric is probably going to be at least 6° C cooler than the skin at any point. The yarn comprising a low moisture absorbing fibre could be made from 100% polyester or other low moisture regain fibre typically 2/30 tex, or 60 tex. This yarn may be suitable for the second weft or also the whole of the warp. Regarding fabric construction it is envisaged that the compound yarn being made up of four yarns and a tape will be both stiff and thick and unsuited to be woven in both warp and weft if the fabric is to be used in apparel, but only used in the warp and weft direction in industrial fabrics.

Super-absorbent fibres and yarns require room to expand as they absorb water. It is therefore essential to leave room within the compound yarn envelope for the super-absorbent yarn to expand. Similarly if the warp and weft threads within the fabric construction bind tightly over the super-absorbing yarn, expansion will not be possible and the capacity of the yarn and fabric to absorb will be restricted. The preferred fabric construction in the warp direction is to have 6 centimetres of threads, a gap of 18 centimetres with no threads 6 centimetres of threads, 18 centimetres with no threads and this sequence repeated across the warp.

Regarding the weft insertion one pick of a super-absorbent compound yarn may be followed by three picks of a resultant 60 tex polyester yarn. This sequence may be repeated four times per inch of fabric. The relatively fine low moisture absorbing yarn may help to prevent fraying of the fabric whilst allowing the fabric to hinge across the weft.

Final fabric stability and prevention of fraying during garment cutting and assembly may be achieved by laminating a lightweight fabric to at least one side of the super-absorbent fabric .

Super-absorbency can be achieved by use of acrylate powders and fibres and these materials can absorb up to 100 times their dry weight in water but in most end uses, particularly in apparel, much lower levels of absorbency are required. There are two major disadvantages with super-absorbent materials: they are not usually washable; and they are slimy and sticky to the touch. The fabric of the present invention deals with both these problems by encapsulating the super-absorbent fibres and yarns within a membrane from which the fibres and polymers have difficulty in escaping. Careful washing trials have been carried out using a conventional washing machine set on delicates where the materials has been weighed dry then wet out and re-weighed sequentially for ten washes where the fabric absorbency remained comparable to the fabric's initial performance. Between 10 and 20 washes the absorbency gradually deteriorated as the acrylate gel leeches out of the cut ends of the compound yarn. At no time did the fabric exhibit any stickiness showing that super absorbent fabric gel was being contained with the exception of the cut ends of the compound yarn.

Examples of fabric made in accordance with the present invention will now be described herein below with reference to the accompanying drawings, in which:

Figure 1 shows a side view of a yarn before the production process ;

Figure 2 shows a side view of a yarn after the production process ; Figure 3 shows a side view of a further embodiment of yarn after the production process;

Figure 4 shows a side view of a further embodiment of yarn after the production process;

Figure 5 shows a side view of a fabric- Figure 5A shows a side view of a further embodiment of fabric;

Figure 5B shows a side view of a further embodiment of fabric;

Figure 6 shows a side view of one part of a further embodiment of fabric;

Figure 6A shows a perspective view of a further embodiment of fabric using the part from Figure 6; and

Figure 6B shows a perspective view of a further embodiment of fabric using the part from Figure 6.

The production of embodiments of compound yarn which includes super absorbent and other supporting fibres, which are capable of wicking moisture or free water are illustrated in Figures 1, 2, 3 and 4.

Figure 1 shows a section of tape of non woven or woven fine pore fabric or membrane (10), preferably 60mm wide, a section of super absorbent yarn (12) made preferably of acrylate and polyester fibres and a section of wicking yarn (14) mainly non absorbent in nature. The tape (10) and yarns (12, 14) are drawn forward through a die or folding device which ensures that the tape is caused to fold around the yarns

Figure 2 shows the first stage of folding where the yarns (12,14) are under tension whilst the tape (10) is caused to wrap around them by passing through a conical shaped die to produce a compound yarn (18).

Figure 3 shows the consolidation of the compound yarn (18) by a fine continuous filament yarn (16) being overwrapped in an anti-clockwise direction round the compound yarn (18) .

Figure 4 shows a further consolidation of the compound yarn (18) by a second fine continuous filament yarn (20) being overwrapped in a clockwise direction round the compound yarn (18). The surface friction, together with the fibrous surface of the tape or membrane (10) results in a stable compound yarn (18) . Figure 5 shows a fabric (30) where a relatively thick compound yarn (18) is woven into the fabric (30) in the weft direction and is held in place by a fine warp and weft yarns (32, 34) . The compound yarn (18) could be woven in the warp with the aid of two beams for simplicity and ease of manufacture and weaving. The compound yarn (18) is woven in the weft.

The use of coarse yarns and low set fabrics to allow maximum absorption of moisture and free water tends to produce unstable fabrics which may give problems during making up and fraying during wear to obviate this problem. The fabric is laminated both back and face with a lightweight fine pore woven, non woven fabric or membrane. Figure 5A show the woven fabric (30) shown in Figure 5 sandwiched between two fine pore woven or non woven fabrics (36) and held there by means of an adhesive, in this case a low melt web adhesive. Figure 5B shows the woven fabric (30) shown in Figure 5 sandwiched between two fine pore woven or non woven fabrics (36) and held in place by lines of sewing thread (38) which quilt the three fabrics (30, 36) together into one compound fabric . Figure 6 shows a loop knit structure (50) which includes super absorbent and non absorbent fibres. It is important both in preparing the fibres to be carded and knitted that a support fibre is blended with the super absorbent fibre as it is a relatively brittle material. It is also important if the fabric is to be adhesively laminated to a fine pore membrane that there are areas of non absorbent knitted loops onto which the laminated adhesive can be stuck as once a super absorbent fibre absorbs water its ability to hold on to an adhesive is lost. The areas of non absorbent fibres can be created by running stripes or rows of loops or by using longer fibres of non absorbent material and shorter absorbent fibres.

Figure 6A shows a fine pore membrane (52) laminated to both sides of a fabric containing super absorbent fibres.

Figure 6B shows a fine pore membrane (52) or fabric quilted to both sides of a fabric containing super absorbent fibres.