GB2379157A

GB2379157A - Sweat management system

Info

Publication number: GB2379157A
Application number: GB0120295A
Authority: GB
Inventors: Paula Louise Forshaw; Adrian Randall; David Congalton
Original assignee: UK Secretary of State for Defence
Current assignee: UK Secretary of State for Defence
Priority date: 2001-08-21
Filing date: 2001-08-21
Publication date: 2003-03-05
Also published as: GB0120295D0

Abstract

The sweat management system, for removing sweat from a body or clothes 3 in close proximity to a body, comprises a sweat transport medium capable of transferring sweat and means for providing a gradient to draw the sweat along the transport medium and away from the body or clothing. The sweat transport medium is preferably provided by the wicking of liquid through or along a textile, which is preferably polyester. The gradient may be provided by the addition of salt to specific regions of a textile, by adding more twist along a length of yarn to encourage liquid flow in the direction of higher twist, by providing an absorbent body 4 that contacts the transport medium, where the absorbent body may be a superabsorbent, or through a combination of the aforementioned methods. Also claimed in a garment for removing sweat from the body. The system is particularly for use with outer clothing where normal evaporation and removal of sweat is either not possible or not sufficient and where the build of sweat can have dangerous consequences, e.g. fire fighting clothing, clothing for arctic conditions etc.

Description

SWEAT MANAGEMENT The present invention relates to a method of removing sweat from a body or clothing and to a garment capable of achieving the same.

The production of sweat is the body's attempt to cool itself by the dissipation of heat energy through evaporation. However, high activity levels cause sweat to be produced faster than it is evaporated resulting on the collection of sweat on the skin and in the clothing. The accumulation of sweat in clothing results in the degradation of thermal insulation and reduces body cooling because the phase change from vapour to liquid is remote from the skin. Furthermore, once activity has ceased the trapped sweat continues to evaporate, removing body heat even when cooling of the body is no longer required which can lead to post exercise chilling. In extreme conditions, the build up of liquid sweat in clothing can be life threatening. For example, in the arctic, liquid sweat trapped in clothing can freeze causing hypothermia and in extreme heat, liquid sweat will increase conduction through the clothing layers of fire fighters where it can be heated to produce steam. Both of these effects will increase the risk of bums to the skin. Liquid sweat is also a problem when wearing impermeable protective equipment such as rubber gloves where it causes maceration and reduces tactility.

Cotton is used in many garments placed next to the skin but cotton absorbs liquid sweat and retains it thus giving rise to the likelihood of post exercise chilling. More modem hydrophobic materials used in commercial next to skin garments, spread liquid sweat across their surface, providing a large surface area from which it can evaporate. In cases of moderate sweat production this will result in the material holding less residual liquid reducing the risk of post exercise chilling. However, in most cases, the next to skin layer forms part of the clothes worn and liquid from the undergarment will pass through the outer layers causing the problems mentioned above. There is thus a need to provide a mechanism whereby liquid sweat can be effectively removed from clothing.

Accordingly there is provided a method for removing sweat from a body or clothing in close proximity to the body which comprises a sweat transport medium and means

providing a gradient to draw the sweat along the transport medium and away from the body or clothing.

The reference to body herein is typically to the human body but it also applies to animal bodies and could, for example include horses which wear coats to help prevent them chilling after they have been exercised.

Sweat will continue to be removed for as long as the gradient is maintained. It is therefore beneficial to maintain the gradient for as long as is required to ensure comfort and safety.

The sweat transport medium is conveniently provided by a wicking of liquid through or along a textile. This typically operates by capillary action. Polyester is an example of a material that can be used as the transport medium. The particular construction of a fabric forming a garment may influence the movement of liquid by a wicking effect but the movement of liquid by wicking is relatively uncontrolled. An alternative transport medium would be cotton or other absorbent fibres may be used. It will be appreciated that garments may be made from materials that would constitute transport mediums. Producing a garment from a material which is also suitable as a transport medium will tend to simplify the inclusion of sweat management in the garment as only the gradient needs to be provided.

The gradient can be provided by different means. One technique is to add salt to specific regions of the textile so that liquid would diffuse towards these regions by osmosis reducing the gradient but providing the capability to remove liquid sweat away from the body. As sweat contains salts it follows that the salt providing the gradient must be at a high enough concentration to effect desired movement along the transport medium. Account may also be taken of the gradient formed by liquids tendency to move from wet to dry areas. However it would be expected that the salt providing the gradient would be at a higher concentration than the salt in the sweat.

By drying the salt the gradient can be returned to its original level. Alternatively a gradient can be provided by adding more twist along a length of yam to encourage liquid flow in the direction of higher twist. As before drying the yam will result in the gradient being restored to its previous level.

A preferred means for providing the gradient is through an absorbent body contacted to the transport medium. By attaching such a material to the transport medium a gradient can be set up which draws liquid along the transport medium and towards the absorbent body. An example of an absorbent body would be silica gel. Ideally a superabsorbent is used as this will tend to maintain the gradient for a longer period.

Superabsorbents are materials such as those found in nappies which are able to absorb relatively large quantities of liquids for a specific volume of absorbent and retain the liquid.

The use of such absorbent mediums to generate a gradient or improve an existing gradient has the added advantage that when it has absorbed a set amount of sweat it can be replaced with a dry absorbent medium thus restoring the gradient. This enables a highly efficient and continuous method of sweat removal to be achieved.

The use of absorbent mediums to generate the gradient which are separable from the transport medium also allows for the prospect of collecting sweat and storing sweat away from the body.

Alternatively a number of approaches each providing a gradient can be adopted to achieve the required level of gradient or help maintain a gradient for longer under similar conditions of sweat generation.

Garments can be designed using the above methodology that will result in greater comfort and safety to the wearer. Such garments may typically be sportswear or outdoor activity attire as the wearer may well be expected to generate significant amounts of sweat.

In a further embodiment there is provided a garment for removing sweat from a body or an undergarment which comprises a sweat transport medium capable of transferring sweat away from the body or undergarment and means providing a gradient to draw the sweat along the transport medium and away from the body or undergarment.

The term"undergarment"is taken to mean an item of clothing in close proximity to the body. It will be appreciated that the undergarment itself can constitute the sweat transport medium and thus in conjunction with the required gradient could be a sweat

; I- removing garment.

The invention will now be described by way of example only and with reference to the accompanying diagrams of which :-

Figure 1 a shows a sample of wicking material, Figure 1 b shows a plan view sample of wicking material with superabsorbent clipped to the sample, Figures 1 c shows side view of Figure 1 b, Figure 2 shows a graphical representation of time against liquid remaining in a sample for a fabric and a fabric in combination with a superabsorbent.

Figure 3a shows a undergarment incorporating a absorbent band, Figure 3b shows a T shirt with a pocket for containing silica gel, and Figure 3c shows an absorbent material in a glove liner.

10ml of distilled water was placed in a watchglass and one end of a 155x38mm strip of wicking polyester was immersed in the liquid. Experiments were conducted both with and without superabsorbent material clipped tightly to the dry end of the wicking strip. After approximately 7 minutes, the sample attached to the superabsorbent had wicked all the liquid from the watchglass to the superabsorbent and although the sample was damp, there was no excess liquid present either on or around the wicking material. However, after the same period of time, the strip that was not attached to superabsorbent was floating in a pool of water with approximately 5mls of water remaining in the watchglass. The experiment was repeated for several different wicking materials and although the rate at which water moved along the samples

varied, in each case the superabsorbent was observed to pull the water from the watchglass along the strip of material. The process stopped once the superabsorbent had reached its full absorption capacity.

In order to quantify how effectively a superabsorbent was able to pull liquid out of materials a drying test was carried out for samples of Coolmax, a trilobal wicking polyester and a 100% cotton cold weather vest with and without superabsorbent attached. As shown in Figures Ib & Ic Circular samples of fabric (1) (surface area 100cm2) with a 20cm2 pad of superabsorbing material (2) folded over one edge so that a surface area of 10cm2 was covered on each fabric face. The experiments were also conducted on fabric samples with no superabsorbent attached as shown by Figure 1 a.

The results of the above experiment are shown in figure 2 and demonstrate that the attachment of superabsorbent to the wicking polyester resulted in the removal of 52% of the initial mass of liquid from the sample in 12 minutes. This compared to a 12% mass loss for the control sample in the same period of time.

Skin wetting occurs when the vapour pressure in the air next to the skin is above saturation point or when the sweat rate exceeds 40gm-2h-'. In the drying experiments

performed approximately 2. 5g of liquid was removed from 100cm2 of material in 12 minutes by folding a 20cm2 piece of superabsorbing material over the sample edge so that an area of 1 Ocm2 covered each sample face. In theory folding and clipping 0. 2m2 of superabsorbing material over the edge of 1m2 wicking polyester so that 0. 1 m2

covered each sample face would enable the removal of 250gm-2 of sweat from the fabric in 12 minutes. Thus even at a maximum attainable sweat rate of lOOOgm-2h-1, the superabsorbent would remove excess liquid from an undergarment, keeping the wearer comfortable and reducing the risk of post exercise chilling.

Figure 3a provides a practical embodiment of the invention. A person wearing a T shirt (3) made from polyester enables the T shirt to act in a wicking manner in relation to sweat. A band (4) of superabsorbent or a band (4) incorporating silica gel is positioned in contact with T shirt across the chest where there is an area of high sweat rate (5). The band (4) provides the required gradient to draw sweat out of the T shirt (3) and into band (4).

Figure 3b shows an alternative embodiment where a T shirt (6) made of cotton has a pocket (7) sown into the chest region. Silica gel (not shown) is then placed into the pocket (7) such that sweat is drawn along the cotton fibres of the T shirt (6) and into the silica gel.

Figure 3c shows a glove liner (8) into which is sewn a pad (9) of superabsorbent.

When sweat arises is will initially be absorbed by the glove liner and then drawn into the superabsorbent.

Claims

Claims 1. A method for removing sweat from a body or clothing in close proximity to the body which comprises a sweat transport medium capable of transferring sweat and means providing a gradient to draw the sweat along the transport medium and away from the body or clothing.
2. A method for removing sweat as claimed in claim 1 wherein the sweat transport medium is provided by a wicking of liquid through or along a textile.
3. A method for removing sweat as claimed in claim 1 or 2 wherein the transport medium is Polyester.
4. A method for removing sweat as claimed in any one of the previous claims wherein the gradient is provided by adding salt to specific regions of a textile.
5. A method for removing sweat as claimed in any one of claims 1 to 3 wherein the gradient can be provided by adding more twist along a length of yam to encourage liquid flow in the direction of higher twist.
6. A method for removing sweat as claimed in any one of the previous claims 1 to 3 wherein the gradient is provided through an absorbent body contacted to the transport medium.
7. A garment substantially as described herein and with reference to the accompanying drawings.

7. A method for removing sweat as claimed in claim 6 wherein the absorbent is a superabsorbent.

8. A method for removing sweat where in the gradient is generated by a combination of the methods provided under claims 4 to 7.

9. A method for removing sweat specifically as described herein and with reference to the accompanying drawings.

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10. A garment for removing sweat from a body or an undergarment which comprises a sweat transport medium capable of transferring sweat away from the body or the undergarment and means providing a gradient to draw the sweat along the transport medium and away from the body or undergarment.

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Amendments to the claims have been filed as follows What we claim is: 1. A garment for removing sweat from a body or clothing in close proximity to the body, which garment comprises a sweat transport medium capable of transferring sweat and means providing a gradient to draw the sweat along the sweat transport medium and away from the body or clothing, wherein the gradient is provided by at least one of the following : i. salt having been added to specific regions of a textile, ii. more twist having been added along a length of yarn to encourage liquid flow in the direction of higher twist, iii. an absorbent body having been contacted to the sweat transport medium.

2. A garment as claimed in claim 1, wherein the absorbent body comprises a superabsorbent.

3. A garment as claimed in either of claims 1 or 2, wherein the sweat transport medium is provided by a wicking of liquid through or along a textile.

4. A garment as claimed in any one of claims 1 to 3, wherein the sweat transport medium is Polyester.

5. A garment as claimed in any one of claims 1 to 4, wherein the sweat transport medium is an absorbent fibre.

6. A garment as claimed in claim 5, wherein the sweat transport medium is cotton.