WO2006100434A1

WO2006100434A1 - Improvements in or relating to spacer fabrics

Info

Publication number: WO2006100434A1
Application number: PCT/GB2006/000896
Authority: WO
Inventors: George Keitch
Original assignee: Mothercare Uk Limited; John Heathcoat & Company Limited; Relyon Limited
Priority date: 2005-03-22
Filing date: 2006-03-13
Publication date: 2006-09-28
Also published as: GB0505839D0; GB2425131A; GB2425131B; EP1863959A1; EP1863959B1

Abstract

A flexible spacer fabric (1) , the fabric having a liquid permeable and breathable upper surface layer (2) , a heat and liquid dissipating spacer layer (8) , and a dimensionally stable lower surface layer (11) , the upper surface layer comprising a knitted mesh comprising sinusoidal mesh strands extending in parallel across the upper face of the fabric, said strands being spaced apart and linked at adjacent points by one or more threads -forming holes, bounded by the mesh strands and threads, of generally oval shape, wherein the average width of the mesh strands in the upper surface layer is from 0.1 mm to 4 mm.

Description

IMPROVEMENTS IN OR RELATING TO SPACER FABRICS

This invention relates to spacer fabrics and more particularly to a novel spacer fabric and a mattress cover and composite mattress construction produced therefrom.

Spacer fabrics have opposite face structures united and held in spaced disposition by linking spacing threads. Spacer fabrics are known, for example, from GB2042003, which describes a liquid absorbing textile product, WO95/16416 which describes a compression bandage, WO95/12018 which describes clothing articles, US5896758 which describes a fabric for footwear and backpacks, WO99/05990 which describes a prosthetic fabric, WO96/01602 which describes a mat, and US5834382 which describes a high temperature resistant covering. The entire disclosures of all these patents are incorporated herein by reference for all purposes.

Ih UK Patent No. GB2305191B there is described and claimed a flexible spacer material, which comprises a fabric, providing a liquid permeable and breathable upper surface and a heat and liquid dissipating spacer layer, and a liquid impermeable lower surface layer. The spacer material is used for the production of mattress covers and more particularly for cot mattresses for babies and young children.

In European Patent No. 1204791B there is described and claimed a flexible spacer fabric, the fabric having a liquid permeable and breathable upper surface layer, the upper surface layer comprising a knitted mesh wherein the average width of the mesh strands in the upper surface layer is from 0.1 mm to 4 mm and wherein the ratio of average hole diameter to average strand width is from 4:1 to 1:2, a heat and liquid dissipating spacer layer, and a dimensionally stable lower surface layer.

In UK Patent NO.2352735B there is described and claimed a flexible spacer fabric, the fabric having a liquid permeable and breathable upper surface layer, the upper surface layer comprising wicking fibres and/or comprising a wicking fibre construction, a heat and liquid dissipating spacer layer, and a dimensionally stable lower surface layer.

The disclosures of UK Patent No.230519lB, European Patent No. 1204791B and UK Patent No. 2352735B are incorporated herein by reference for all purposes.

Cot mattresses produced using the spacer materials and fabrics described in GB2305191B, EP1204791B and GB2352735B have ^' vastly improved properties over conventional cot mattresses and the products, sold under the name SLEEPRIGHT (RTM) cot mattress by Mothercare UK Limited, have proved to be commercially extremely successful .

Aspects of cot mattresses for infants that are extremely important include breathability, which gives an improved safety factor for the cot mattress, and air flow, which reduces the risk of over-heating, thereby leading to greater comfort for the infant. Also important are the liquid transport properties of the fabric, which ideally should enable rapid conveyance of body fluids away from the body region, reducing discomfort for the infant.

A further factor that ^'influences the acceptability of a cot mattress is the "feel" of the. fabric surface, which should preferably be smooth and soft to the touch. In this respect an improvement in the handle and feel of the existing products would be desirable. The existing fabric has an upper surface layer comprising a knitted mesh which does not sit flat to the surface and does not have a soft "woven fabric" handle and feel. Nevertheless, the properties of breathability, air flow and liquid transport are inextricably linked to surface design and it has hitherto been found very difficult to provide improved softness of feel and handle without prejudicing the other desirable properties of the cot mattress. -Attempts to improve the soft feel of the upper surface layer by brushing, for example, have not proved to be successful.

The present invention provides a flexible spacer fabric having a smooth, relatively flat, upper surface comprising a knitted mesh that emulates the soft feel and handle of a woven fabric, whilst substantially maintaining, or enhancing, the above-mentioned other desirable properties.

In a first aspect, the present invention provides a, flexible spacer fabric having a smooth, relatively flat, upper surface, the fabric comprising a liquid permeable and breathable upper surface layer, a heat and liquid dissipating spacer layer, and a dimensionally stable lower surface layer, wherein the upper surface layer comprising a knitted mesh comprising sinusoidal mesh strands extending in parallel across the upper face, of the fabric, said strands being spaced apart and linked at adjacent points by one or more threads forming holes, bounded by the mesh strands and threads, of generally oval shape, wherein the average width of the mesh strands in the upper surface layer is from 0.1 mm to 4 mm.

In a further aspect, the invention provides a mattress cover material which comprises a flexible spacer fabric according to the invention and a liquid impermeable lower surface layer. In another aspect the invention provides a cot mattress comprising a foam plastics core or a spring mattress core and a cover comprising an outer layer comprising a flexible spacer fabric according to the first aspect of the invention and a liquid impermeable inner layer.

In a still further aspect, the invention provides a cot mattress comprising a foam plastics core or a spring mattress core, a cover comprising a flexible spacer fabric according to the invention, and, arranged between the mattress core and the cover, a liquid impermeable layer.

Preferred fibres for use in the upper surface layer are multifilament synthetic yarns. Suitable synthetic fibres include polyesters and polyamides, although polyesters are preferred, due to their greater heat stability. Preferred multi-filament yarns have a dTex of from 40 to 340, more preferably from 40 to 180.

The upper surface layer is preferably such that liquids and air can easily pass there through and into the spacer layer and the spacer fabric is preferably such that it has an ability to conduct liquid away from the surface and dissipate it through the fabric structure, and such that it permits passage of air through the structure.

The upper surface layer is preferably a warp knitted mesh, having generally oval-shaped holes as hereinbefore described of a size such that liquids can pass therethrough. The mesh size of the upper surface layer is preferably as large as possible to allow for drainage and ventilation purposes, but should not be so large as to cause discomfort when placed next to the skin. The oval- shaped holes preferably have a length of from 3.5 to 4.5 mm and a width of from 2 to 3 mm. A mesh having an average hole area of from 7 to 9 mm², preferably around 8 ram² has been found to give particularly good results.

The average width of the individual sinusoidal mesh strands in the upper surface layer is from 0.1 to 4 mm, preferably from 0.5 to 3mm, such as, for example, about 1 to 2 mm. Each mesh strand preferably comprises from 4 to

6 fibres in the strand. The sinusoidal mesh strands preferably have a periodicity (distance between successive peaks or troughs) of from ^'4 to 8mm, preferably from 5 to 7mm, for example, about 6mm.

Preferably the ratio of the average area of a hole of the mesh to the average width of a mesh strand in the upper surface layer is from 9:1 to 7:2, for example, 5:1.

The oval-shaped holes are formed by one or more threads joining adjacent sinusoidal mesh strands together. Preferably the parallel sinusoidal strands are offset from one another lengthwise, such that a peak of one strand faces a trough of an adjacent strand. The peaks and troughs of adjacent strands are preferably spaced apart by a distance of at least 0.25mm, more preferably from 0.4 to 1.2mm and most preferably from 0.5 to 1.0mm.

Facing peaks and troughs are joined by one or more threads, preferably two, more preferably three and most preferably four threads, or more, to form the oval-shaped holes. The threads are preferably parallel, preferably straight and preferably of length from 0.4 to 1.2mm, most preferably 0.5 to 1.0mm. Preferably the threads have a dTex of from 40 to 180.

Preferably the upper surface layer of the spacer fabric is such that liquids of viscosity of at least 20 dynes per centimetre and more preferably of at least 30 dynes per centimetre can pass through the upper surface and into the spacer layer without lying on the surface. Preferably the upper surface of the spacer fabric has a grade of less than 1 when tested in accordance with the Oil Repellency Rating AATCC method.

The breathability of the upper surface layer is preferably such that, when placed face down on the fabric, a baby can continue to breath relatively normally.

A suitable air permeability test providing a measure of the breathability of a fabric, i.e. the ease with which air passes through the fabric structure, is BS 4578:1970 (1991) Measurement of Restriction of Airflow. Preferably the spacer fabric has a value of less than 5 mm H₂O, more preferably less than 2.0mm H₂O, most preferably less than lmm H₂O, when tested in accordance with BS 4578:1970 (1991).

Preferably the upper surface layer comprises a warp knitted mesh of multifilament yarns.

Preferably there are incorporated in the upper surface layer inherently wicking fibres or a wicking fibre construction as described and claimed in UK Patent NO.2352735B.

In this specification the term "wicking fibre" is intended to mean a fibre which, by virtue of its shape and configuration, and/or filament dTex, has inherent wicking properties, whereby liquid can be transported along the fibre by capillary action. Similarly the term "wicking construction" is intended to mean a fibre construction, comprising two or more fibres, which construction has inherent wicking properties, whereby liquid can be transported along the fibre construction by capillary action. Preferred wicking fibres for use in the upper surface layer are multifilament synthetic fibre yarns sold for their inherent wickability. Such fibres have enhanced capillary action by virtue of their shape and configuration. The enhanced wicking properties of so- called wicking fibres can be achieved, for example, by various different fibre cross-sectional structures, preferably providing at least one longitudinal channel which permits faster liquid' transport by capillary action. All wicking fibres have a capability of wicking at a significantly greater rate and to a greater distance than conventional multifilament fibres of similar dTex. They can, for example, have a complex cross-section which provides a plurality of longitudinal channels to conduct liquid along the fibre at a rate and distance greater than a comparable conventional multifilament fibre with a circular cross-section. Fabrics knitted from inherently wicking fibres can have a drying rate of up to 20%, more preferably 30% and most preferably 50% faster than cotton, and up to 5%, and more preferably 10%, faster than conventional synthetic fibres. Preferably a fabric made from an inherently wicking fibre has a moisture loss of at least 5%, more preferably at least 10%, greater than a fabric made from a conventional synthetic fibre having a circular cross-section after 30 minutes.

Suitable synthetic fibre yarns include polyesters and polyamides, although polyesters are preferred, due to their greater heat stability. Preferred multi-filament yarns have a dTex of from 40 to 340, more preferably from 40 to 180. An example of a suitable wicking fibre is CoolMax™, which is a four channel Dacron™ polyester fibre with a special cross-sectional structure comprising three intersecting circles manufactured by Du Pont. Another potentially suitable wicking fibre is CoolMax Alta™, also manufactured by Du Pont. Wicking fibre constructions that can be used in the upper surface layer usually comprise two or more synthetic fibres of different dTex, knitted in layers. A typical wicking fibre construction comprises an upper layer of a relatively coarse fibre and a lower layer of a relatively fine fibre or microfilament .

Suitable synthetic fibres for the wicking fibre construction include polyesters and polyamides, although polyesters are preferred due to their greater- heat stability. The wicking fibre construction can, for example, comprises an upper layer of a coarse multifilament yarn having a filament dTex of from 6 to 3, and a lower layer of a microfilament yarn having a dTex of from 1.1 to 0.3.

In addition to its inherent wicking properties, the upper surface layer can also aid liquid transport by allowing liquids to pass through itself into the spacer layer.

In certain embodiments of the invention, at least the upper surface layer of the spacer fabric can also comprise an anti-bacterial yarn which is preferably of the type that also retards the growth of mould, mildew and fungus. Incorporation of an inlay of the antibacterial yarn can provide a safer and more hygienic spacer fabric. Other inlays which can be used include, for example, thermoregulating fibres.

The linking threads of the spacer layer preferably comprise a mono-filament yarn which traverses back and forth between the upper and lower surfaces. By omitting multi-filament linker threads from the spacer layer, the air volume of the spacer layer can be increased, providing improved air permeability and heat dissipation. In a preferred spacer fabric of the invention, the number of mono-filament linker threads in the spacer layer is preferably from 100 to 400 threads per square centimetre, for example about 286 threads per square centimetre.

Whilst the mono-filament linking threads in the spacer layer can be individually spaced apart and perpendicularly arranged with respect to the upper and lower surface layers, they are preferably arranged such that each pair, or group, of threads is in the form of a V-shape, when the fabric is viewed in cross-section, with the angle of the V preferably being from 5° to 55°, for example about 27° to about 32°. The V-shaped pairs or groups of threads can form a zig-zag pattern, and each individual thread can have a horizontal midsection which is inlaid into the upper surface layer.

Preferably at least 50% and more preferably 100% of the linking threads are arranged in V-shaped formations.

By arranging for pairs or groups of threads linking the upper and lower surfaces to lie at opposed angles to the perpendicular distance between the upper and lower surfaces, it is possible to improve the resistance of the spacer fabric to "flopping over" when subjected to a compressive force. This "flopping over" is highly undesirable since it can result in the complete flattening of the spacer fabric and a loss of the spacer layer with its properties of breathability and heat dissipation. As the linking threads are angled in alternate directions the spacer fabric can achieve a comfortable resilient feel whilst still retaining breathability, heat dissipation and a resistance to crushing.

The linking threads preferably have a sufficient stiffness to resist complete crushing of the fabric by the distributed weight of a baby, and yet have sufficient resilience to impart springiness or "give" to the fabric for comfort. Preferred mono-filament yarns for use as linking threads have a dTex of from 22 to 115, and can be made, for example, from a polyamide such as Nylon, a polypropylene, or most preferably, a polyester.

Preferably the spacer fabric of the invention is such that the spacer layer requires a work of compression, as measured by BS 4098:1975 of at least 50 J/metre², preferably at least 60 J/metre², with a maximum of around 350J/m² and a thickness recovery of at least 50%, preferably at least 75%, and a compression recovery of at least 65%, preferably at least 75%.

Preferably the spacer fabric of the invention is such that in the spacer layer the ratio of the volume of free space to the volume of linker threads is greater than 40, preferably greater than 100.

In preferred embodiments of the invention, the upper surface layer has a construction wherein the monofilament linker threads of the spacer layer are effectively surrounded by softer multi-filament yarns in order to give a still softer surface feel. This construction can be achieved, for example, using a Liba- DPL machine, and a combination of closed and open stitches relative to the different yarns and threads. Preferably an open stitch is applied to the surface multi-filament yarns, and a closed stitch to the mono- filament linker threads.

Surrounding the mono-filament linker threads with multifilament yarns in the upper surface layer spreads the point of load of each mono-filament linker thread over a larger area and imparts greater resilience and improved compression anti-fatigue characteristics to the fabric. In preferred spacer fabrics according to the invention the surface mesh is fully supported by the mono-filament linker threads.

The dimensionally stable lower surface layer of the spacer fabric of the invention is preferably knitted with stitches having a plurality of loops, which can be achieved, for example, by using two guide bars instead of one, and using a Liba-DPLM machine. The number of stitches is reflected in the gauge of the knitting machine used, and preferably the machine has a gauge of at least 16 and preferably 16, 22, 24, or 28. By "dimensionally stable" is meant that the lower surface layer retains its integrity even after washing and crumpling.

In certain embodiments of the invention, the lower surface of the spacer fabric is provided with a liquid impermeable layer which can be obtained, for example, by direct coating of the lower surface of the fabric with a liquid-impermeable polymeric material, by impregnation of a liquid-impermeable polymeric material, or by transfer coating, or laminating a film of liquid-impermeable polymeric material thereto, to provide a tightly adherent, liquid-impermeable, backing layer or impregnated layer.

Preferably the liquid-impermeable layer is provided by laminating a flexible backing layer of a suitable polymeric material, for example, a polyurethane film, to the lower surface of the fabric by means of an adhesive. The layer of polymeric material is preferably from 10 to 30 microns in thickness, and good results and good flexibility have been achieved using a 25 micron thick polyurethane layer. Other polymeric film materials, such as, for example, polyethylene and polyvinylchloride may also be used in appropriate circumstances. Where an adhesive is used for laminating, this may be solvent or heat activated, or cold-cured but the amount of heat and pressure used in the lamination process must neither be sufficient to compress the resultant laminate unduly, nor to cause permanent damage thereto. Preferably the adhesive, when set, forms a flexible film in order to prevent crumpling and flexing of the material without cracking of the film.

Preferably the backing layer achieves a pass as waterproof when tested in accordance with BS EN 20811:1992.

The backing layer is preferably such that it can be repeatedly machine washed and dried in a tumble dryer without undue shrinkage or permanent damage thereto .

The lower surface layer of the spacer fabric is preferably a multi-filament or spun-filament warp knitted fabric, and, for example, there may be used a multifilament yarn having a dTex of from 40 to 230, for example, about 78 dTEX. Polyamide or polyester yarns are examples of suitable multifilament yarns which can be used, although polyester yarns are preferred.

The spacer fabric as a whole should of course have a high wi^'ckability, which is defined as the ability of the fabric to conduct liquid away from the area of initial contact and form a relatively thin liquid film within the fabric structure. Wickability of the fabric as a whole can be measured in accordance with TTM 1428:92 (FDC.348) by suspending test specimens from spring clips vertically over a beaker of distilled water and measuring the height to which the liquid rises in a given time. Preferably the spacer fabric is such that the wicked liquid rises to a height of at least 50mm, preferably at least 100mm, when tested in both the warp and weft directions, in a time of 30 minutes. Prior to testing the specimens are conditioned for a minimum of 16 hours in a standard atmosphere of 20°C/65% Relative Humidity ±2.

A further measure of the ability of the spacer fabric to conduct liquid away from its surface and dissipate it through the fabric structure is a water dispersion test in which a solution containing a suitable dye is used to measure the spread of liquid into and through the fabric. In this test, a measured amount of liquid (0.5ml) is applied to the fabric upper surface. The dimensions of the area stained due to the spread of liquid are measured over time. In a preferred spacer fabric in accordance with the invention the dimensions of the spread of water containing dye are at least 5.5cm by 2.5cm and the spread of liquid reaches near equilibrium in about 15 minutes.

The fabric preferably has good heat dissipation, such that it can dissipate heat rapidly away from a hot body. Preferably the fabric is such that the temperature of the fabric when placed under a hot plate with an initial temperature of 34°C does not exceed 25°C and more preferably 22°C after 10 minutes.

In certain preferred constructions according to the invention, where the liquid impermeable layer is not laminated to the spacer fabric, it is found that the spacer fabric makes less noise when its surface is rubbed softly, thereby improving the comfort of a cot mattress produced therefrom by reducing rustling.

In one embodiment according to the present invention, a cot mattress can be formed by providing a mattress core, a mattress cover comprising a spacer fabric according to the invention, and a liquid impermeable layer therebetween. For example, a mattress core, which can be either a foam plastics core or a sprung interior mattress core, can be provided with a liquid impermeable waterproof underlay, and the spacer fabric of the invention can be formed into a removable mattress cover therefor. An advantage of this construction is that the spacer fabric without the waterproof laminated layer is likely to be more resistant to creasing and distortion when washed at high temperatures. In this embodiment the mattress core is preferably completely enclosed with a waterproof film layer in .order to prevent liquids from reaching the core. Complete enclosure of a foam mattress core, for example, by the use of a water proof plastics underlay, is important, since if the mattress becomes wet it can form depressions which do not recover when dry.

The resistance of a laminated mattress cover according to a further aspect of the invention, wherein the cover comprises the spacer fabric and a waterproof plastics backing layer, to distortion and creasing during a 60°c wash, may be improved by cross-linking the plastics layer, either before or after the lamination step. Cross-linking can be carried out by, for example, electron beam irradiation, chemical cross-linking, or other techniques known to the art. In this aspect of the invention, cross-linking of the waterproof backing can be applied to laminated mattress covers according to the present invention, and also to the backing layer of laminated spacer materials produced in accordance with GB2305191B.

The foam plastics core or body of a foam mattress according to the invention preferably comprises an open cell polymeric foam material, for example, foamed polyurethane, and very good results have been obtained using Vitafoam (RTM) , a polyurethane foam comprising Melamine as a fire retardant additive. Preferably the foam plastics core or body is permeable to air, although with certain spacer materials of high breatheability this may .not be essential. Perforation of the foam plastics core is not usually required.

Where the spacer fabric is used as a mattress cover or mattress protector, it is preferably removable from the mattress core or body for washing purposes and, for example, the cover material or mattress protector may be a loose cover, or provided with a zip at one or more edge regions to permit such removal.

In order to reduce the manufacturing cost of the cot mattress, it is possible to provide the spacer fabric as the top surface layer only of the mattress, the sides and lower surfaces being made of cheaper standard mattress cover fabric material.

In preferred embodiments of the invention, the mattress achieves a pass under BS Standard 7177 for Resistance to

Ignition of Mattresses, Divans and Bed Bases, and BS

Standard 1877 Fire Retardancy Test for Mattresses and

Bumpers for Childrens' Cots, Perambulators and Similar

Domestic Articles and is devoid of fire retardant additives comprising antimony, phosphorus or arsenic.

Spacer fabrics can be knitted, for example, on Raschelmachines with two needle bars. Depending upon the nature of the spacer fabric and its physical requirements, a minimum of four guide bars, and normally four to six or more guide bars, are used. In addition to the requirements set out hereto, the thickness of the yarn used for the spacer threads is influenced by the distance between the upper and lower surfaces, the desired softness of the upper surface and whether the central layer is knitted with one guide bar or with two guide bars knitting in opposition to each other. The manufacturing methods for spacer fabrics are discussed in the brochure "Spacer Fabrics - Manufacturing Methods and Applications" published in 1994 by Karl Mayer Textilmaschinenfabrik GmbH, the entire disclosure of which is incorporated herein by reference for all purposes. In the spacer fabrics of the present invention, the distance between the upper and lower surfaces, that is, the width of the spacer layer, is preferably from 2 to 6mm, more preferably about 3mm.

Preferred embodiments of a spacer fabric and a cot mattress and mattress cover according to the invention are described in the following Examples:

EXAMPLE 1

A spacer fabric in accordance with the invention is knitted on a RD6N machine using two needle bars and six guide bars. The sequence of operation is as follows:

GUIDE BAR 1 6-6-3-3/0-0-3-3/6-6-3-3/0-0-3-3/6-6-4-4/ 3-3-6-6/9-9-6-6/3-3-5-5//

GUIDE BAR 2 3-3-6-6/9-9-6-6/3-3-6-6/9-9-6-6/3-3-4-4/ 6-6-3-3/0-0-3-3/6-6-3-3/0-0-3-3/6-6-4-4//

GUIDE BAR 3 1-0-0-0/0-1-1-1//

GUIDE BAR 4 1-0-2-3/1-0-2-3//

GUIDE BAR 5 2-3-1-0/2-3-1-0//

GUIDE BAR 6 0-0-0-2/2-2-2-0//

Guide bars 1 and 2 form the top mesh surface.

Guide bars 4 and 5 could have different movements for the linking threads, which could in an alternative manufacturing method use only one instead of two guide bars. It would also be possible to use two half set guide bars in opposition instead of one.

Guide bars 5 and 6 could again have different movements for the production of different fabric backing types .

The construction notation is given in steps of 2 i.e. 0-1-2-3-4, where each number represents a movement (or non-movement of the guide bar over one needle space) .

Eg. 0-1 is a movement over one needle. 0-2 is a movement over two needles.

The numbers between the / marks represent the movement with respect to a needle bar or bars.

Eg. 1-0-1-2// will mean the guide bar knitting over both needle bars (to use the linking threads) .

1-0-1-1// will mean the guide bar knitting only on one needle bed, as there is no movement (2-2) on the second needle bar. In a preferred embodiment, by way of example only, the yarn dTEX (thickness) is as follows:

Bars 1, 2 and 3 - 78 dTEX polyester Bars 4 and 5 - 33 dTEX polyester Bar 6 - 78 dTEX polyester

The resultant spacer fabric has a thickness of 3mm, an uppppeerr ssuurrffaaccee mmeesshh hhoollee aavveerraagge .area of 8mm² and an average mesh strand width of 1.5mm.

The spacer fabric can be slit to 60cm wide and made up into a zip-off cover for a cot mattress. The foam core of the cot mattress is a 10cm thick polyurethane foam material of grade 35M.

All the polyester yarns used in the manufacture of the spacer fabric exemplified, and the polyurethane foam of the mattress core, are chosen to be substantially free of arsenic and antimony, and to contain less than 12 parts per million, preferably to be substantially free, of phosphorus.

Whilst there is no specific test for fabric "feel" or "handle", subjectively, a spacer fabric, mattress cover and mattress produced as described above have improved softness to the touch, and have a feel closely resembling comparable soft fabric materials. Samples of the spacer fabric, mattress cover and mattress produced as described above were subjected to the following tests, with results and conclusions as set out below. The comparison fabric is a fabric produced in accordance with GB2305191B, EP1204791B and GB2352735B.

1. Air Permeability Test

This is to assess the breathability of the fabric, i.e. the ease with which air passes through the fabric structure.

Test Method: BS 6595:1985 clause 3.3; BS 4578:1970 (1991) Measurement of Restriction of Airflow.

The closer the result is to zero the better the airflow through the mattress cover. The results are as follows:

New fabric . Comparison

Upper fabric surface 2.3 mm H₂O 1.4 mm H₂O

The results indicate that the spacer fabric cover of the present invention has a slightly lower permeability than the comparison, but still excellent breathability. After washing in accordance with BS49236A at 40⁰C and line drying, the air flow restriction of the spacer material mattress cover of the invention is still very low (3.1 mm H₂O) .

2. Liquid Dissipation Tests

These demonstrate the ability of the fabric to take liquid away from the surface and dissipate it through the fabric structure.

2(a) Liquid Flow Test

Liquid flow from the surface of the fabric into the structure of the fabric is measured according to AATCC test method 118-1989.

The closer the rating is to zero, the more liquids are taken into the fabric. The new fabric had an initial rating less than 1, which indicates that liquids- of all tested viscosities soaked into the fabric structure and proves liquid would not sit on the fabric surface.. After washing and dry cleaning the rating was still less than 1.

2(b). Wicking ^'test (IHTM017 based on TTM1428:92 (FDC. 348)

Test specimens are suspended over a beaker of distilled water and the height to which the liquid rises is measured over time.

The new fabric and the comparison are tested in both fabric directions.

The results are as follows:

Wicking Rate Comparison New Fabric

Warp direction 1 min 39mm 45mm

Warp direction 5 mins 71mm 78mm Warp direction 30 mins Exceeded clips 128mm

@ 24 min

Warp direction 1 hr Exceeded clips @

36 min

Weft direction 1 min 38mm 23mm

Weft direction 5 mins 70mm 44mm

Weft direction 30 mins exceeds clips 76mm

@ 29 mins

Weft direction >lhr Exceeded clips @

88 min

Whilst the results for the new fabric are slightly inferior to those of the comparison, they are still very good, especially in the warp direction, and it can be seen that the wicking rate of the new fabric in the warp direction actually exceeds that of the comparison initially.

3. Dimensional Stability to Washing

This test was carried out using wash cycle 2A, 60° C with tumble drying in accordance with BS EN 26330:1994.

New Fabric Comparison Dimensional change length -2.0% length -2.8% width -3.0% width -2.7%

The results show that both the new fabric and the comparison had minimal dimensional change after washing and tumble drying. The new fabric had less length-wise shrinkage but slightly more width-wise shrinkage.

4. Thickness Compression and Recovery Test

Five samples of the fabric of the invention are tested following the procedure described in BS4098:1975, and the results averaged.

New Fabric (averaged) Comparison Original thickness 3.0mm 4.1mm

Compression 2.6mm 3.2mm

Thickness r.ecovery 87.6% 86.4% i Compression recovery 82.9% 82.7%

The results show that the new fabric has a slightly improved thickness recovery and compression recovery after compression.

5. Wettability of Fabric

Wettability was tested in accordance with BS 4554:1970. Initially both the new fabric and the comparison were wetted in less than one second. After washing the new fabric wetted in from three to 27 seconds.

6. Fire Retardancy Test A mattress made from a fabric in accordance with the invention is tested for fire retardancy to the standard laid down in the Furniture and Furnishing (Fire Safety) Regulations 1988. The result is a pass.

An embodiment of a spacer fabric according to the invention will now be described, by way of example only, with reference to the accompanying Drawings, in which:

Figure 1 shows a plan view of the upper face of the fabric; and

Figure 2 shows the fabric in sectional side elevation.

Referring to Figure 1, the spacer fabric illustrated generally at 1 has an upper face 2 comprising a warp knitted multifilament mesh having parallel sinusoidal strands 3 of width 2mm and periodicity (distance between successive peaks or troughs) of 6mm. The parallel sinusoidal strands are offset from each other such that a peak 4 of one ^• strand is adjacent a trough 5 of an adjacent strand. Adjacent peaks 4 and troughs 5 of the strands are joined by four straight threads 6 of length 0.5 to 0.6mm, forming oval holes 7 of length 4mm and width 2.5mm. The strands 3 lie flat to the surface of the spacer fabric such that the fabric has a smooth, comfortable feel and are spaced apart to give a soft handle to the fabric.

In Figure 2 there is shown the spacer layer 8, having monofilament polyester spacer threads^' 9, disposed in generally V-shaped groups 10, with an acute angle a, as illustrated, between threads of opposed inclination. The lower surface 11 of the spacer fabric 1 is knitted from multifilament polyester threads to form a substantially dimensionally stable layer. Individual spacer linking threads such as 12, illustrated as a thicker line, have sections 13, 14, angled in opposed directions, and a horizontal midsection 15 which is inlaid in the upper surface layer 2.

The reader's attention is directed to all papers and documents which are filed concurrently- with or previous to this specification in connection with this application and which are .open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) , may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features .

The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A flexible spacer fabric, the fabric having a liquid permeable and breathable upper surface layer,, a heat and liquid dissipating spacer layer, and a dimensionally stable lower surface layer, wherein the upper surface layer comprising a knitted mesh comprising sinusoidal mesh strands extending in parallel across the upper face of the fabric, said strands being spaced apart and linked at adjacent points by one or more straight threads forming holes, bounded by the mesh strands and threads, of generally oval shape, wherein the average width of the mesh strands in the upper surface layer is from 0.1 mm to 4 mm.

2. A fabric according to Claim 1, wherein the upper surface layer comprises a warp- knitted mesh of synthetic fibres.

3. A fabric according to Claim 1 or '2, wherein the average length of a hole in the mesh is from 3.5 to 4.5mm and the average width of a hole is from 2 to 3mm.

4. A fabric according to any one of claims 1 to 3, wherein the mesh average hole area is from 7 to 9mm²

5. A fabric according to any one of the preceding claims, wherein the average width of the sinusoidal mesh strands in the upper surface layer is from 0.5 to 3mm.

6. A fabric according to any one of the preceding claims, wherein the sinusoidal mesh strands comprise from 4 to 6 fibres per strand.

7. A fabric according to any one of the preceding claims, wherein the periodicity of the sinusoidal mesh strands is from 4 to 8mm.

8. A fabric according to any one of the preceding claims, wherein the parallel sinusoidal strands are offset from one another lengthwise, such that a peak of one strand faces a trough of an adjacent strand.

9. A fabric according to claim 8, wherein the peaks and troughs of adjacent strands are spaced apart by a distance of from 0.4 to 1.2mm.

10. A fabric according to claim 8 or 9, wherein facing peaks and troughs are joined by up to four threads, to form the oval-shaped holes.

11. A fabric according to claim 10, wherein the threads are parallel .

12. A fabric according to claim 10 or 11, wherein the threads are straight.

13. A fabric according to any one of claims 10 to 12, wherein the threads are of length from 0.4 to 1.2mm.

14. A fabric according to any one of the preceding claims, wherein the ratio of the average hole area to the average width of the mesh strands in the upper surface layer is from 9:1 to 7:2.

15. A fabric according to any one of the preceding claims, wherein the upper surface layer is knitted from multifilament synthetic yarn.

16. A fabric according to Claim 15, wherein the multifilament synthetic yarn is a polyester.

17. A fabric according to Claim 15 or 16, wherein the multifilament yarn has a dTEX of from 40 to 180.

18. A fabric according to any one of the preceding claims, wherein the upper surface layer is such that liquids of viscosity of at least 30 dynes per cm can pass through the upper surface and into the spacer layer without lying on the surface.

19. A fabric according to any one of the preceding claims, wherein the upper surface of the fabric has a grade of less than 1 when tested in accordance with the Oil Repellency Rating AATTC Method.

20. A fabric according to any one of the preceding claims, which has a value of less than 2.0mm H₂O of water, when tested in accordance with BS4578:1970.

21. A fabric according to any one of the preceding claims, wherein the upper surface layer comprising wicking fibres or a wicking fibre construction

22. A fabric according to Claim 21, wherein the wicking fibres comprise multifilament synthetic fibre yarns.

23. A fabric according to Claim 21 or 22, wherein the multifilament wicking fibre yarns have a dTEX of from 40 to 180.

24. A fabric according to Claim 21, wherein the wicking fibre construction comprises an upper layer of a coarse multifilament yarn having a filament dTEX of from 6 to 3 and a lower layer of a micro filament yarn having a dTEX of from 1.1 to 0.3.

25. A fabric according to any one of the preceding claims, in which the linking threads of the spacer layer consist solely of a monofilament yarn.

26. A fabric according to claim 25, wherein the number of monofilament linking threads in the spacer layer is from 100 to 400 threads per square cm.

27. A fabric according to claim 25 or 26, wherein the monofilament threads are arranged such that each pair, or group, of threads is in the form of a V-shape.

28. A fabric according to claim 27, wherein the angle of the V is from 5° to 55°.

29. A fabric according to claim 27 or 28, wherein substantially a 100% of the linking threads are arranged in V-shaped formations.

30. A spacer fabric according to any one of claims 25 to 29, wherein individual monofilament linking threads have sections angled in opposed directions and a midsection which is inlaid in the upper surface layer.

31. A fabric according to any one of claims 25 to 30, wherein the monofilament linking threads have a dTex of from 22 to 115.

32. A fabric according to any of claims 25 to 31, wherein the monofilament linking threads comprise a polyester.

33. A spacer fabric according to any one of claims 25 to 32, wherein the upper surface layer has a construction wherein the monofilament linking threads of the spacer layer are surrounded by softer multifilament yarns.

34. A spacer fabric according to claim 33, wherein an open stitch has been applied to the multifilament yarns and a closed stitch has been applied to the monofilament linking threads.

35. A fabric according to any one of the preceding claims, such that the spacer layer requires a work of compression as measured by BS4098:1975 of at least 60 J/m².

36. A fabric according to any one of the preceding claims, which has a thickness recovery of at least 75%.

37. A fabric according to any one of the preceding claims, which has a compression recovery of at least

/JO l

38. A fabric according to any one of the preceding claims, such that in the spacer layer the ratio of the volume of free space to the volume of linking threads is greater than 100.

39. A fabric according to any one of the preceding claims, wherein the dimensionally stable lower surface layer is knitted with stitches having a plurality of loops .

40. A fabric according to any one of the preceding claims, wherein the lower surface layer comprises a multi filament or spun-filament warp knitted fabric.

41. A fabric according to claim 40, wherein there is used a multi filament yarn having a dTex of from 40 to 230.

42. A fabric according to claim 40 or 41, wherein the multi filament yarn comprises a polyester.

43. A fabric according to any one of the preceding claims, which when subjected to a wickability test as hereinbefore defined is such that the wick liquid rises to a height of at least 100mm, when tested in both the warp and weft directions, in a time of 30 minutes.

44. A fabric according to any one of claims 1 to 43 substantially as described in the Example.

45. A mattress cover which comprises a flexible spacer fabric according to any of claims 1 to 44 and a liquid impermeable lower surface layer.

- 46. A mattress cover according to claim 45, wherein the liquid impermeable lower surface layer is laminated to the spacer fabric.

47. A mattress cover substantially as hereinbefore described.

48. A cot mattress comprising a foam plastics core or a spring mattress core and a cover comprising an outer layer of flexible spacer fabric according to any one of claims 1 to 44 and a liquid impermeable inner layer.

49. A cot mattress according to claim 48, which is provided with a liquid impermeable waterproof underlay and wherein the spacer fabric is formed into a removable mattress cover therefor.

50. A cot mattress according to claim 48 or 49, wherein the mattress core comprises an open cell polymeric foam material.

51. A cot mattress as substantially as hereinbefore described.

52. A flexible spacer fabric substantially as hereinbefore described with reference to and as illustrated in the accompanying Drawings .