MULTI-LAYERED NON-WOVEN INSULATING TEXTILE MATERIAL

Abstract

A multi-layered non-woven hygroscopic fibrous textile material and method of making said material is disclosed. The fibres of the material extend across the thickness of the material and respectively opposite outer layers of fibres are fixed in a matted state relative to the inner fibres. The extent of matting is sufficient to increase thermal insulation per unit thickness relative to the inner fibres, whilst still permitting the outer layer fibres to allow air circulation between and through the outer fibres, to thereby permit moisture retention or release.

Description

[0001] It is well known from e.g. U.S. Pat. No. 1,601,625 that the hygroscopic qualities of natural wool can be used in packaging in order to absorb moisture and/or to thermally insulate the contents, such as by the use of layers of wool fixed to the walls of a cardboard pizza storage carton as is shown in WO2010/119140. However, as will be appreciated, the relatively bulky nature of wool can take up significant volume within the packaging and requires containment in e.g. individual pockets or pillows, one for each wall of the storage carton, which increases the complexity of the packaging and is conducive to mass manufacture only for specifically dimensioned and shaped cartons, where the crease lines are between respectively adjacent pockets or pillows of wool.

[0002] Packaging of the foregoing type can find use in many industry sectors, such as in the medical field where pharmaceuticals or donor organs are required to be transported over relatively long periods, such as 24 to 48 hours, but where it is essential to keep the contents of the packaging within a relatively closely defined thermal range. This may be hot, warm, cool or cold, depending upon the contents of the packaging but where, in each case, the hygroscopic properties of wool are able to assist in providing the necessary insulation and minimising the thermal gradient until delivery of the package.

[0003] An obvious problem with packaging which either contains individual pockets or pillows of wool or similar hygroscopic fibres such as jute and cotton is that they limit airflow therebetween or therethrough, thereby adversely affecting the otherwise beneficial hygroscopic properties of the fibre. Similarly, where e.g. wool is fixed to the walls of a carton as shown in WO2010/119140 this problem is also compounded by the use of a suitable adhesive, which also acts to limit the ability of the fibres to absorb or release moisture and is not readily usable where the carton is made of different materials, such as aluminium or plastic.

[0004] The present invention is derived from the realisation that there is a need for a simpler and more effective approach which may be used to insulate cartons made from all kinds of materials whilst retaining the benefits of the hygroscopic properties of e.g. wool used as the insulating medium, although the invention is not limited to the use of wool.

[0005] According to a first aspect of the invention there is provided a multi-layered non-woven hygroscopic fibrous textile material in which the fibres extend across the thickness of the material, respectively opposite outer layers of fibres being fixed in a matted state relative to the inner fibres, the extent of matting being sufficient to increase thermal insulation per unit thickness relative to the inner fibres, whilst still permitting the outer layer fibres to allow air circulation between and through the outer fibres, to thereby permit moisture retention or release.

[0006] With this arrangement the textile material effectively "biomimics" a fleece of wool on a sheep, in that the outer layers of the material are matted, corresponding to the matted and hence dense wool immediately next to the skin of a sheep and the matted and dense wool on the outside of the fleece which thereby improves the insulation of the textile material without impairing the benefits of the hygroscopic properties of the fibres.

[0007] Conveniently, the textile material is comprised of fibres which have been loose needled felted prior to the respectively opposite outer layers being matted or compressed so that the inner fibres retain their relatively open nature and this may be conveniently assisted by the use of coarse wool fibres where typically the fibres have a thickness greater than about 27 microns.

[0008] The matting or compression of the respectively opposite outer layers of the textile material may conveniently be accomplished by hydroentanglement using respectively opposite water jets, although needle punching, chemical bonding or other methods may instead be used to compress or matt the respectively opposite outer layers.

[0009] Accordingly, a second aspect of the invention extends to a method of making a multi-layered non-woven hygroscopic fibrous textile material in accordance with the first aspect of the invention including the steps of orientating strands of hygroscopic fibres to form a relatively loosely bonded multi-layered fibrous material and thereafter matting or compressing respectively opposite sides of the material to produce an insulating textile material.

[0010] Conveniently, the method according to the second aspect includes matting or compressing the respectively opposite outer layers by the use of hydroentanglement, where the outer fibres of the material are matted together through the use of jets of liquid such as water and thereafter dried. Alternatively, the matting of the respectively opposite outer layers may be by needle punching or felting, or chemical bonding using a suitably breathable adhesive, such as starch. Other possible methods of matting the outer layers are not excluded.

[0011] The invention will now be described, by way of example only, with reference to the accompanying drawings in which:

[0012] FIG. 1 is a side elevation of a slab of fibrous textile material according to the first aspect of the invention; and

[0013] FIG. 2 is a schematic view of a method of making the textile material of FIG. 1 according to the second aspect of the invention.

[0014] Referring firstly to FIG. 1 there is shown an enlarged side view of part of a slab of fibrous textile material shown generally at 1 comprising a lightweight inner layer 2 and more dense respectively opposite outer layers 3, 4, with all three layers having strands of hydroscopic fibres in the form of wool orientated in the same direction. Each of the outer layers 3, 4 are originally formed from the same relatively lightweight inner material 2 but have been subsequently compressed or matted together to form respectively opposite outer skins surrounding the inner layer 2 and thereby giving, amongst other things, mechanical strength to the material 1 so that it may be cut to any desired length or shape for subsequent use as insulation within e.g. a rigid container such as a box or between side walls of a container requiring thermal insulation. The compression of the respectively opposite outer layers 3, 4 is not complete, and is such that it still allows the fibres within those layers to absorb or release moisture without acting as a pneumatic barrier to the less dense inner layer 2. This construction closely models or "biomimics" that of a sheep's fleece and it has been found that provided the compression or matting of the layers 3, 4 is not too great so as to form a thermally conductive barrier the insulation values are potentially even better for the less-dense inner layer 2.

[0015] The textile material 1 shown in FIG. 1 may be used as it is by being cut into any required length or shape, or it may be incorporated into or onto other layers of material. For example reflective foils or rigid foams may be used to assisting insulation and impact absorption etc.

[0016] FIG. 2 shows one of several methods that have been used to construct the textile material of FIG. 1 through the process of hydroentanglement where an initially wet but uncompressed moving ribbon of unwoven textile material 1a is compressed by the use of oppositely disposed jet strips 5, 6 to reduce the thickness of the outer layers to form the textile 1 as shown in FIG. 1. This is achieved by the jet strips 5, 6 being composed of multiple high pressure nozzles spraying fine jets of water (shown arrowed) at a pressure of e.g. 100 bar out of each side of the textile 1 before it is finally formed and thereafter dried for use. With this arrangement, by way of example, an initially 30 mm thick ribbon of loose needled 800 gsm carded coarse wool was reduced to a final thickness of 20 mm, with the matted and compressed outer layers each being 4 mm thick. The end result showed significantly improved thermal insulation performance as compared to the original 30 mm thick ribbon, with a net 10 mm space saving. Hence, by taking a "biomimicry" approach the invention provides an elegantly simple solution to the general problem of providing high performance insulation which, after use, can biodegrade or be recycled for whatever purpose.

Claims

1. A multi-layered non-woven hygroscopic fibrous textile material in which the fibres extend across the thickness of the material, respectively opposite outer layers of fibres being fixed in a matted state relative to the inner fibres, the extent of matting being sufficient to increase thermal insulation per unit thickness relative to the inner fibres, whilst still permitting the outer layer fibres to allow air circulation between and through the outer fibres, to thereby permit moisture retention or release.

2. A textile material according to claim 1, wherein the textile material is comprised of fibres which have been loose needled felted prior to the respectively opposite outer layers being matted or compressed so that the inner fibres retain their relatively open nature.

3. A textile material according to claim 1, wherein the matting or compression of the respectively opposite outer layers of the textile material is accomplished by hydroentanglement.

4. A textile material according to claim 3, wherein the hydroentanglement uses respectively opposite water jets.

5. A textile material according to claim 1, wherein the matting or compression of the respectively opposite outer layers of the textile material is accomplished using at least one of needle punching or chemical bonding.

6. A method of making a multi-layered non-woven hygroscopic fibrous textile material according to claim 1, the method including the steps of orientating strands of hygroscopic fibres to form a relatively loosely bonded multi-layered fibrous material and thereafter matting or compressing respectively opposite sides of the material to produce an insulating textile material.

7. A method according to claim 6, further comprising matting or compressing the respectively opposite outer layers by the use of hydroentanglement.

8. A method according to claim 7, further comprising drying the material.

9. A method according to claim 6, further comprising matting or compressing the respectively opposite outer layers by the use of at least one of needle punching or chemical bonding.

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