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Title:
HEAT GENERATING FABRIC COMPOSITION
Document Type and Number:
WIPO Patent Application WO/2019/171084
Kind Code:
A1
Abstract:
A fabric composition for use in a garment, such as a maritime safety vest, which undergoes an exothermic reaction when in contact with water to produce heat and mitigate the effects of cold exposure from the water. The fabric composition comprises: at least one layer of fabric; a hydrateable metal compound (22a), such as MgCl2.2H20 or Mg(CIO4)2 having the general formula MXa.bH2O (where b can be from 0 to 10) and Xa.bH2O usually includes at least one oxygen atom; and a metal oxide such as CaO having the chemical formula MdO. A series of semi-permeable bags containing, alternately, the hydrateable metal compound (22a) and the metal oxide (22b), may be provided between two layers of fabric (11,12). One further advantage of the fabric is that the reaction products are not gaseous or toxic and remain in an unchanged solid state.

Inventors:
BUCKNALL, David (Unit 1 District 10,25 Greenmarket, Dundee Tayside DD1 4QB, DD1 4QB, GB)
LAMONT, Simon (Unit 1 District 10,25 Greenmarket, Dundee Tayside DD1 4QB, DD1 4QB, GB)
Application Number:
GB2019/050662
Publication Date:
September 12, 2019
Filing Date:
March 11, 2019
Export Citation:
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Assignee:
IRON OCEAN LIMITED (Unit 1, District 1025 Greenmarket, Dundee Tayside DD1 4QB, DD1 4QB, GB)
International Classes:
A41D13/005; B63C11/28; A41D31/06; A41D31/12
Attorney, Agent or Firm:
HGF LIMITED (Document Handling - Aberdeen, 1 City Walk, Leeds West Yorkshire LS11 9DX, LS11 9DX, GB)
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Claims:
Claims

1. Fabric composition suitable for use in a garment comprising:

at least one layer of fabric;

a hydratable metal compound having the chemical formula MXa.bhhO;

wherein M is a first metal cation, X is an anion, a is at least 1 and at most 4, and b is zero or at least 1 and at most 10; and

a metal oxide having the chemical formula M’dO

where M’ is a second metal cation and d is at least 1 and at most 2.

2. A fabric composition as claimed in claim 1 , wherein the at least one layer of fabric is a first layer of fabric and the fabric composition comprises a second layer of fabric and at least a first semi-permeable bag attached to the first layer of fabric, the first bag containing the metal compound and at least a second semi-permeable bag attached to the first layer of fabric, the second bag containing the metal oxide.

3. A fabric composition as claimed in claim 2, comprising at least twenty first semi- permeable bags containing the metal compound, and at least twenty semi-permeable bags containing the metal oxide.

4. A fabric composition as claimed in claim 2 or claim 3, wherein the at least a first semi-permeable bag and the at least a second semi-permeable bag further contain one or more hydrophilic binders.

5. A fabric composition as claimed in clam 4, wherein the one or more hydrophilic

binders have a water droplet contact angle on a smooth surface thereof of at most 50°, optionally less than 40°, optionally less than 30°.

6. A fabric composition as claimed in claim 4 or claim 5, wherein the one or more

hydrophilic binders remain substantially undissolved in water for at least 30 minutes, optionally at least 1 hour.

7. A fabric composition as claimed in any one of claims 2 to 6, wherein the first and second semi-permeable bags have a polygonal shape with at least four sides.

8. A fabric composition as claimed in claim 7, wherein the first and second semi- permeable bags have a polygonal shape with six or eight sides thus being hexagonal or octagonal.

9. A fabric composition as claimed in any one of claims 2 to 8, wherein the weight of the metal compound and any binder in each of the at least a first semi-permeable bag is less than 5g, especially in the range of 0.1 -1 g, and the weight of the metal oxide and any binder in at least a second semi-permeable bag is less than 5g, especially in the range of 0.1 -1 g.

10. A fabric composition as claimed in any preceding claim, wherein at least one of the metal compound and the metal oxide are in the solid phase such that on contact with water they undergo an exothermic reaction resulting in only non-gaseous products, preferably only solid products.

11. A fabric composition as claimed in any preceding claim, wherein the at least one layer of fabric is a non-woven layer of fabric.

12. A fabric composition as claimed in any one of claims 2 to 11 , wherein one of the first and second layers of fabric comprises at least one channel.

13. A fabric composition as claimed in any preceding claim, wherein at least one of the layers comprises a semi-permeable layer.

14. A fabric composition as claimed in any one of claims 2 to 13, wherein one of the first and second layers of fabric is formed from water resistant fabric.

15. A fabric composition as claimed in any preceding claim, wherein MXa.bhhO

comprises at least one oxygen atom.

16. A fabric composition as claimed in claim 15, wherein b is at least 1 and at most 10.

17. A fabric composition as claimed in any preceding claim, wherein the metal compound and the metal oxide are provided as particles in the range of 1nm - 10pm.

18. A fabric composition as claimed in claim 17 wherein the particles are coated in a cellulosic-based polymer.

19. A fabric composition as claimed in any preceding claim, wherein the first metal cation and the second metal cation are cations from a group 1 or group 2 metal especially group 2. 20. A fabric composition as claimed in any preceding claim, wherein the first metal cation is a cation from a metal chosen from the list consisting of magnesium, calcium, silicon, aluminium and phosphorus especially magnesium.

21. A fabric composition as claimed in any preceding claim, wherein a is 1 or 2,

especially 2.

22. A fabric composition as claimed in any preceding claim, wherein the anion is a

halide. 23. A fabric composition as claimed in claim 22, wherein the halide is chosen from the group consisting of chlorine, bromine and iodine, especially chlorine.

24. A fabric composition as claimed in any one of claims 1 to 21 wherein the anion is perchlorate.

25. A fabric composition as claimed in any preceding claim, wherein the value of b is in the range of at least 1 to at most 5, especially 2.

26. A garment comprising the fabric composition as claimed in any one of claims 1 to 25.

27. A garment as claimed in claim 26 being a vest or a jacket.

Description:
HEAT GENERATING FABRIC COMPOSITION

This invention relates to a fabric composition for a safety garment for use in maritime environments.

Workers in offshore or maritime environments run the risk of falling overboard or otherwise into water. The cold exposure from the water in many areas can quickly result in hypothermia or death. Immersion suits can be worn which can provide some insulation, and/or seal some of the body from direct contact with water, to reduce the rate of heat loss. Heat loss nevertheless continues and will result in death if the person is not rescued in a relatively small time window.

US2012/0118282 discloses a safety device for incorporation into work clothes where elemental sodium is provided which on contact with water creates a gas to inflate a circular tube to seal points, such as an ankle, through which water could enter the clothing. Heat is also generated by the reaction of sodium with water.

Whilst generally satisfactory, the inventor of the present invention considers that at least one improvement can be made for safety garments.

According to a first aspect of the present invention, there is provided a fabric composition suitable for use in a garment comprising:

at least one layer of fabric;

a hydrateable metal compound having the chemical formula MX a .bH20;

wherein M is a metal cation, X is an anion, a is at least 1 and at most 4, and b is zero or at least 1 and at most 10.

The hydrateable metal compound may be a metal hydrate.

On contact with water, the hydrateable metal compound undergoes the following chemical reaction:

MX a .bH 2 0 + CH 2 0 > MX a .(b+c)H 2 0 + heat wherein c is at least 1. Therefore, even if b is zero, the exothermic reaction is a hydration reaction causing the metal compound to be hydrated, or further hydrated. The hydrateable metal compound is hereinafter referred to as the‘metal compound’. c can be 1 , 2 or more c is normally 10 or less, optionally 6 or less b+c in total is normally 10 or less, optionally 6 or less. The value of b may be zero or in the range of 1 to 5.

Thus, in contradistinction to the teaching of US2012/0118282 supra no gas is released when the metal compound comes into contact with water. However, an exothermic reaction occurs which produces heat to mitigate the effects of cold exposure when immersed in water.

One advantage of using a metal hydrate is that the reaction is reversible when the metal hydrate is dried. For certain embodiments therefore, the fabric composition may be re-used.

Another advantage is that during the reaction with water the state of matter is conserved. Thus, the metal compound is in a solid state prior to the reaction and will remain solid state as the reaction progresses. This avoids emission of gases, which may be flammable or toxic.

A further advantage is that during the reaction with water no corrosive substances, such as hydrochloric acid, are released.

Preferably the fabric composition further comprises a metal oxide having the chemical formula M d O, wherein M is a metal cation, d is at least 1 and at most 2.

On contact with water, the metal oxide undergoes the following chemical reaction: heat wherein d can be 1 or 2.

The metal oxide also remains in the solid state during the reaction.

An advantage of using a metal oxide as well as a metal compound is that the levels and/or lifetime of heat output may be controlled, as the compounds have different associated rates of heat release upon their contact water. For example, the metal oxide normally provides a greater heat for a shorter period of time, compared to the metal compound. Preferably at least 80wt%, optionally at least 90wt%, or substantially 100wt% of the metal compound and, optionally, the metal oxide, undergoes the reaction upon the contact with water, thereby releasing heat.

If the fabric composition comprises the metal oxide, then the metal oxide is normally provided separately from the metal compound.

The metal may be a group 1 or group 2 metal, particularly a group 2 metal. The metal may be chosen from the list consisting of magnesium, calcium, silicon, aluminium and

phosphorus. In the metal compound, the preferred metal is magnesium or calcium, especially magnesium. In the optional metal oxide, the preferred metal is magnesium or calcium, especially calcium.

The value of a is typically dependent on the valency of the metal a is normally 1 or 2.

Where the metal is magnesium, a is 2.

Whilst the group X a .bhhO may include the value of b= 0, and therefore anhydrous, it preferably includes at least one oxygen atom, either because b is from 1 to 10, or through the anion including oxygen. There may optionally be at least 2 or 4 or more oxygen atoms.

The anion may be a halide. The halide can be chosen from the group consisting of chlorine, bromine and iodine. One preferred halide is chlorine.

Especially preferred embodiments do not produce gas or toxic substances when they undergo the above exothermic reaction. Thus, when X is a halide, b is normally at least 1 and at most 10.

Another option for X, especially where b is zero, is perchlorate ((CIO4) '1 ) or sulphate (SO4 2'

Such hydrated halides or perchlorate or sulphate do not produce a gas (or toxic substances such as HCI) when undergoing the above exothermic/hydration reaction; in contrast to, for example, anhydrous magnesium chloride.

In one embodiment M = magnesium and X = (CIC>4)2 which undergoes the following exothermic reaction:

Mg(CIC>4)2 + ZH2O -> Mg(CI04)2.zH20 + heat where z is 1 or greater, usually 1 to 6.

The metal compound, and optionally, the metal oxide may be mixed with one or more binders.

Preferably the one or more binders are hydrophilic and may be polymers. Hydrophilicity may be quantified by means of static contact angle. The one or more binders may have a water droplet contact angle of at most 50 degrees, usually less than 40 degrees, preferably less than 30 degrees, on a substantially smooth surface.

Preferably the one or more binders have a low dissolution rate in water. Typically, the one or more binders remain substantially undissolved for at least 30 minutes, preferably at least 1 hour or at least 4 hours.

The one or more binders may comprise one or more polymers, especially hydrophilic polymers. The one or more polymers may be chosen so as to achieve the desired low dissolution rate in water. This may be done by using one or more cross-linked polymers, that are substantially insoluble, such as sodium polyacrylate. Optionally, substantially uncross-linked one or more polymers may be used, that are soluble, such as poly(ethylene glycol); however, normally of molecular weight greater than 5kg/mol, preferably greater than 10kg/mol, such as to reduce their rate of dissolution in water.

The one or more binders may comprise one or more super absorbent hydrogels.

The one or more binders may act as a water sink and help control the water diffusion rate towards the metal compound, and optionally, the metal oxide. The one or more binders may further trap the water prolonging the heat output effect.

The at least one layer of fabric may be a first layer of fabric, and a second layer of fabric may also be provided. Thus, there may be a first outer and a second inner layer of fabric. Outer’ and‘inner’ are relative to the person wearing the garment in use and therefore the design of the garment to be worn accordingly.

The outer and inner layer of fabric are typically provided back to back. At least one of the layers of fabric may be a porous fabric such as a semi-permeable membrane. This is more usually the outer layer but not necessarily so. For example, certain embodiments allow for water to enter between the garment and the wearer. Thus, the inner layer may be formed from porous fabric to allow water from between the wearer and the garment to proceed through the layer for contact with the metal compound and optionally, the metal oxide.

Various options are polyester, polyurethane, nylon-based fabrics or other fabrics.

The level of permeability of the at least one of the layers of fabric may be chosen to provide a specific rate of heat release upon contact of the metal compound and, optionally, the metal oxide, with water. The permeability of the outer layer may be greater than 1cm 3 /cm 2 .s, normally greater than 2cm 3 /cm 2 .s, preferably greater than 3cm 3 /cm 2 .s especially in the vicinity of semi-permeable bags such as on the torso of a garment.

Instead of, or in addition to having a porous layer of fabric, at least one, normally a plurality of, channel(s) may be formed in the at least one layer of fabric to allow water access to the metal compound and, optionally, the metal oxide.

The outer layer of fabric may be formed from waterproof or water-resistant fabric, and may be made from commercially available waterproof fabrics, such as Gore-Tex®.

The inner layer is typically a comfort layer made from commercially available fabric such as merino wool. It typically separates the metal compound and, optionally, the metal oxide from the wearer preventing damage, or its wear when in use, and may also provide some insulation.

The metal compound and, optionally, the metal oxide may be provided between the outer layer and the inner layer. The metal compound and, optionally, the metal oxide may be provided on an inner face of one of the layers, especially the outer layer.

The metal compound and, optionally, the metal oxide may be provided on the fabric in a variety of ways. For certain embodiments the metal compound and, optionally, the metal oxide, optionally, mixed with the one or more binders, may be provided in semi-permeable bags affixed to at least one of the layers of fabric. The semi-permeable bags may be polygonal, preferably hexagonal or octagonal, but other shapes may also be used, for example, circular. The semi-permeable bags may be of various sizes, but are typically smaller than 2cm, optionally less than 1cm in diameter.

The fabric composition may comprise a single semi-permeable bag, but usually multiple bags are present, preferably at least twenty for the metal compound optionally more than fifty or more than 100; and where a metal oxide is used, the same number of semi- permeable bags containing metal oxide. For at least twenty metal oxide semi-permeable bags and twenty metal compound semi-permeable bags, a row of such bags typically alternates between metal oxide semi-permeable bags and metal compound semi-permeable bags.

The spacing between the semi-permeable bags when used as part of the fabric composition may be at least 0.1 , typically at least 0.25, of the diameter of a typical semi-permeable bag.

Nevertheless, additionally or alternatively, the relative number of the semi-permeable bags comprising the metal compound and the metal oxide may be adjusted. Thus, different rates of heat release and, therefore, different levels of heat released at any particular instant may be controlled.

The metal compound and, optionally, the metal oxide and, further optionally, the one or more binders, may be provided in bulk. The weight of the metal compound, or optionally, the metal oxide (and the one or more binders if present) in each semi-permeable bag is typically less than 5g, preferably within the range of 0.1 - 1g.

The semi-permeable bags may be heat-sealable.

The semi-permeable bags may be referred to as pockets or pouches. Optionally, the pouches may be formed out of a third layer of fabric and a fourth layer of fabric. Each layer may comprise one or more semi-pouches, arranged such that when the third and fourth layers are brought together, one or more pouches are formed. The third and fourth layers of fabric may be heat-sealable. The third and fourth layers of fabric may have open weave.

Alternatively (or additionally), the metal compound and, optionally, the metal oxide may be provided in at least one layer of fabric. For example, the metal compound and, optionally, the metal oxide may be provided in at least one intermediate layer of fabric between the inner and outer layers of fabric. The layers of fabric may be woven or non-woven although non-woven fabrics are slightly preferred especially for the intermediate layer.

Optionally, the metal compound and, optionally, the metal oxide and, further optionally the one or more binders, may be provided as particles in the range of 1nm - 10 pm, optionally 100 - 1000 nm, more optionally 400 - 600 nm.

The particles may be encapsulated by a polymer, such as a cellulosic-based polymer, to form a partially permeable water barrier layer, for example using emulsion polymerization. A suitable method for coating the particles in this way is described in Saladn, F at a/ 1 the disclosure of which is incorporated herein in its entirely, by way of reference.

The particles may then be mixed with a binder that may be cross-linked once applied to the surface of one or more layers. One suitable binder is polyacrylate.

Alternatively, the encapsulated particles may be incorporated into the textile fiber spinning solution and the particles co-spun so that they are incorporated into the textile fibers as described in Iqbal, K et al 2 the disclosure of which is incorporated herein in its entirety, by way of reference.

The polymer will normally be water permeable, to allow water transport through the matrix. Nylon is one suitable polymer to encapsulate the metal compound and, optionally, the metal oxide.

A garment may comprise the fabric composition. The garment may be a vest or a jacket. It may be worn as an intermediate garment along with an undervest providing more insulation, and an over-garment providing cut and/or fire-resistant properties. The semi-permeable bags may be arranged such as to cover at least 50%, normally at least 60%, preferably at least 70% of the surface of the garment. The fabric composition provided herein may especially be useful in the body torso portion of the garment to provide heat to the body’s core. The semi-permeable bags may be arranged such as to cover at least 80%, preferably at least 90% of the surface of the garment. For certain embodiments, the sleeves of the garment are made from conventional fabric material. An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Fig. 1 is perspective view of a garment according to the present invention;

Figs. 2a and 2b are illustrative perspective views of two-layer embodiments of a fabric composition used for the garment of Fig. 1 ;

Fig. 3 is an illustrative perspective view of a three-layer embodiment of a fabric composition used for the garment of Fig. 1 ;

Fig. 4 is a further illustrative view of the Fig. 3 fabric composition when exposed to water

Fig. 5a is a graph showing the maximum temperature output based on the amount of magnesium perchlorate; and,

Fig. 5b is a graph showing the maximum temperature output based on the amount of calcium oxide;

Fig. 5c is a graph showing the temperature output of magnesium perchlorate over time using different binders; and,

Fig. 5d is a plot of TGA data showing relative weight loss of microencapsulated metal chloride hydrate during from hydration-dehydration.

Fig. 1 shows one embodiment of a garment 10 which can be worn in hazardous locations, such as offshore on oil and gas platforms (or travel thereto), vessels or the like.

In the Fig. 2a embodiment, the fabric composition of the garment 10 has two layers. An outer semi-permeable layer 11 and an inner comfort layer 12.

The outer layer 11 is made from, for example, nylon, and has a metal compound provided thereon, as a series of semi-permeable bags 22 patched on to the inner surface of the layer 11. The bags may be made from Nylon. The metal compound in this embodiment is Mg(CI0 4 ) 2 .

The inner comfort and insulating layer 12 is made from merino wool.

When in contact with water, the water proceeds through the semi-permeable layer 11 , contacts the metal compound bags 22 on its inner side, resulting in an exothermic chemical reaction according to the equation below.

Mg(CIC>4)2 + ZH2O > Mg(CI04)2.zH20 + heat z is normally in the range of 1 - 6.

The resulting heat generated at least mitigates the heat loss caused by the exposure to the water. For certain embodiments, this can result in heat transfer from the fabric to the person wearing the garment.

In the Fig. 2b embodiment, the fabric composition of the garment 10 has two layers, as in Fig. 2a. In this embodiment, half of the semi-permeable bags 22a comprise Mg(CIC>4)2 mixed with sodium polyacrylate binder, alternate with the other half of the semi-permeable bags 22b comprising CaO mixed with sodium polyacrylate binder. Thus, upon contact with water, the following exothermic reactions occur:

Mg(CI0 4 )2 + ZH 2 0 Mg(CI0 4 )2.zH 2 0 + heat

heat

The rate of heat release in the first reaction is slower than in the second reaction. Thus, by varying the relative number of bags 22a comprising the Mg(CI0 4 ) 2 and bags 22b comprising the CaO, the rate of total heat release and, thus, the level of heat released an any particular instance can be controlled.

The fabric of the garment 10 in the Figs 3 and 4 embodiment has three layers 111 , 112, 113 shown in Figs. 3 and 4. The first outer layer 111 is made from waterproof fabric and comprises channels 21 to allow the ingress of a small amount water, when immersed, towards the intermediate layer 113 which is a non-woven fibre containing the metal compound dispersed therein. The fibre may be made from nylon.

Contact with water, as shown in Fig. 4 results in an exothermic reaction transferring heat to the user as shown by arrows 23.

Experiments

In one experiment, a mixture of the active component consisting of sodium polyacrylate physically mixed as dry powders with the magnesium perchlorate or calcium oxide was used. The powders were dried and then ground in an electronic grinder to both reduce the powder sizes, but also to maximise the mixing of the components. The percentage ratio of the sodium polyacrylate to metal compound was varied from 0:100 to 100:0. Fig. 5a shows the resulting maximum temperature as a function of percentage of

magnesium perchlorate mixed with sodium polyacrylate. A maximum of 85 °C is obtained from the pure magnesium perchlorate.

Fig. 5b shows the resulting maximum temperature as a function of percentage of calcium oxide mixed with sodium polyacrylate. A maximum of 115 °C is obtained from the pure calcium oxide.

The time scale of heat release is a function of both the binder content and the relative water permittivity of the outer fabric layers of the garment. Control of the water permittivity allows the heat output to be maximised and also the length of time over which the heat is maintained above the desired 40 °C minimum.

By changing the polymer binder, changes to the rate of heating and also temperature over 40 °C can be controlled. This is shown in Fig. 5c, which is a plot of temperature of magnesium chloride compound for two different hydrophilic polymer binders: sodium polyacrylate (solid line) and poly(ethylene glycol) (dashed line).

In another experiment, encapsulated metal hydrate particles (MgCh.ehhO and CaCh.ehhO) were prepared using the method described in Salaun et al. In a calorimeter the time dependent heat changes produced during water sorption by the encapsulated particles have been studied. After formation the particles were dehydrated by annealing in an oven from 25 to 130 °C at a heating rate of 1 K/min and then holding at 130 °C for up to 100 mins. After this period all the particles were shown (using a thermogravimetric analyser TGA) to be dehydrated. Using a TGA, the dehydration/hydration cycle has been studied, with the Ca salt showing both a faster hydration rate and larger percentage water uptake compared to the Mg salt (as shown in Fig. 5d). Maximum temperature output observed with the MgCh.ehhO cellulosic encapsulated particles is reduced from 85 to 32 °C due to the encapsulation.

Improvements and modifications may be made without departing from the scope of the invention.

References

1. Salaun, F.; Devaux, E.; Bourbigot, S.; Rumeau, P., Development of a precipitation method intended for the entrapment of hydrated salt. Carbohydrate Polymers 2008, 73, (2), 231-240.

2. Iqbal, K.; Sun, D., Development of thermo-regulating polypropylene fibre containing microencapsulated phase change materials. Renewable Energy 2014, 71 , 473-479.