WO2005052235A1

WO2005052235A1 - A soft, cushioning ans stiffening spacer fabric

Info

Publication number: WO2005052235A1
Application number: PCT/DK2004/000804
Authority: WO
Inventors: Bettina Balslev SØRENSEN
Original assignee: Tytex A/S
Priority date: 2003-11-25
Filing date: 2004-11-22
Publication date: 2005-06-09

Abstract

The present invention relates to a spacer fabric having cushioning properties comprising a first outer layer, a second outer layer, and an intermediate spacer layer integrated with said first and second outer layer. The invention is new and characterised in that at least part of one of the outer layers comprises hybride yarns, said hybrid yarns comprising at least one type of thermoplastic melting fibre and at least one type of structural fibre. Said fibres having different temperature profiles, wherein the thermoplastic fibre is adapted to melt, wet out and stiffen the fabric structure at a temperature at which the structural fibre remains substantially unaffected, and subsequently be moulded or in other ways shaped.

Description

A SOFT, CUSHIONING AND STIFFENING SPACER FABRIC

Field of the Invention The present invention relates to a spacer fabric having cushioning properties comprising a first outer layer, a second outer layer, and an intermediate spacer layer integrated with said first and second outer layer. The knitted spacer fabric according to the present invention may for instance be used in products for orthopaedic purposes such as orthopaedic splinting, orthopae- die casting, orthopaedic bracing, orthopaedic soft goods and support as well as sports bracing and sports goods equipment and work wear, for preventive as well as for treatment purposes. Said product groups will in the following be referred to as orthopaedic applications or orthopaedic products.

Background Art For these orthopaedic applications it is of high importance that the materials used have certain built-in properties. These properties may for instance be skin friendliness, a cushioning effect for comfort or support, breathability, moisture handling properties, protection from impact, compression as well as rigidity and stiffness for supporting, stabilizing or immobilizing a limb, joint, muscle, bone or other body part. Other important properties are resiliency, elasticity or flexibility in order to provide orthopaedic products with good fitting properties, which may accommodate a certain range of sizes and body shapes and at the same time provide the right amount of power, i.e. support and compression. For orthopaedic applications within support, splinting, bracing and casting, the textile or other soft mate- rials used are often combined with additional stiffening elements in the form of rigid or semi-rigid supports, such as stays, polymer materials, impregnation resins, metal splints or the like. These elements can i.e. be coated or laminated on, sewn on, moulded on, welded on, riveted on or in other ways adhered to/assembled with the soft materials, or they can be separate and just used in conjunction with the softer materials. In any case, the softer materials contribute with cushioning, softness, moisture handling, skin friendli- ness, breathability, support and the like, and the stiffening elements contribute with stiffness and further support . Rigid braces may for instance consist of several individual elements such as a pre-shaped rigid brace with a synthetic or cotton padding and/or stockinette. The rigid brace may for instance also comprise a foam, neoprene, felt, textile or other soft, cushioning liner and may include a hinge to allow the joint to bend either into extension and or flextions. Braces exist as off the shelf braces, custom modified braces and custom made braces. Off the shelf braces often cannot be modified, wherefore the brace is provided in several standard sizes for each of the right and left extremities, and are often made adjustable, e.g. with a hook and loop closure. In spite of this, the fit may not always be very accurate. Braces for custom modification are normally pre-shaped, but can be modified to fit the individual user by e.g. forming with a heat gun. Custom- made braces are often produced individually by making a body case base plaster, where after a mould is built, wherein the brace is moulded by e.g. vacuum moulding, and the soft parts are added. The custom-made brace is very time-consuming to make and thus expensive, and the user often has to wait for a considerable period of time to get the brace. In any case, during use of the brace the combination of a rigid brace with a conventional soft e.g. foam pad- ding often traps or promotes heat and moisture in the skin area, which may lead to skin maceration and skin breakdown. Rigid braces are often heavy and/or thick, due to the combination of large rigid parts with a thick cushioning inner layer and assembly means, and can thus be uncomfortable to the wearer. Some braces cannot be washed due to the often moisture absorbing thick inner layers that will take a very long time to dry, also due to the covering rigid brace that further slows down the water penetration and drying speed. Furthermore, shower- ing can be a problem to the wearer, where the brace will have to be removed during showering, or be covered by a water-proof material, i.e. a polybag. Furthermore, it is often important in orthopaedic products that the product is permeable to air and mois- ture. Often this is attempted to be obtained by providing perforations or holes in the stiffening and/or soft elements . This may be a further production step that makes the end products more expensive, unattractive and often it does not ensure adequate breathability. An example of this is perforation of neoprene, where tests have shown that in spite of the perforation, the breathability and moisture handling properties are unsuitable for use for medical bandages, due to moisture build up on the human skin, cf. the article "Physiological Demands on Materials for Bandages" of Dr. Volkmar T. Bartels and Prof. Dr. Karl-Heinz Umbach. Orthopaedic support products exist in numerous variants for the different body parts, such as knee, foot, wrist, back, neck, elbow etc. In general they may consist of soft materials only or a combination of soft materials and stiffening elements, depending on the level of sup- port and immobilizing needed. They may be adjustable (e.g. hook&loop closure), and may in some areas contain stiffening elements such as semi-rigid or rigid stays, flexable hinges, polymer laminated materials or the like. The stiffening elements may be pre-shaped or be shape- able. The shapeable stiffening elements may expediently be moulded or formed for instance by hand to the body part to be supported, whereby a tight fit is obtained. However, during the production of these orthopaedic products, the soft material, such as neoprene, laminated foam, elastic or spacer fabric, is first cut out in one or more pieces having suitable size and form. The anatomically adapted shape of the support product is thereafter obtained by joining together, for instance by sewing, welding, gluing and/or moulding, the different soft parts. During the joining or after, the stiffening elements are incorporated in the product by sewing, encapsulating, coating, laminating, welding or other methods. This involves many time-consuming processes and thereby makes the end product expensive. Furthermore the seams or joints can be uncomfortable and create pressure marks on the wearer's skin. In order to limit the number of seams, joints and/or number of manufacturing steps, a need has risen for in- corporating the stiffening elements directly in the soft materials . Casts and splints are used especially for the treatment of fractures, to fixate the broken bones from outside by the cast. Beside the treatment of fractures, casts are used to relieve pain for example after strains, after surgery or during inflammations . Some casting and splinting materials are stiff and un-flexible when stored, but soften when dipped in warm water for a certain period of time. These materials have typically made of a narrow textile fabric, e.g. nonwoven, cotton or synthetic mesh, covered with a layer of polymer material that is stiff at room temperature, but softens at a low temperature (below 100°C) . Before the applica- tion of the casting material, the limb is covered with a layer of cushioning soft material cut to size and shape i.e. a thick non woven felt, and the softened layer of splinting or casting material is then wrapped around said textile layer, and the limb is kept still while the poly- mer coated fabric stiffens and dries. If the splinting or casting material during the stiffening does not achieve the right form and fit due to for instance too slow application or mal-positioning or movement of wearer, the splint or casting may not be re- mouldable, as it cannot practically be dipped in water again, when it has been applied to the textile liner and is on the wearers limb. Some splinting and casting materials are flexible when stored in sealed condition, but reacts with water or the humidity of the air and starts to harden when they are exposed to water or air. These materials often consist of thicker (for splints) or thinner (for casting) textile or glass fibre fabrics that are impregnated with e.g. polyurethane resins, that chemically reacts and cures by the contact to air or water, these often being referred to as water- or air-hardenable materials, or plaster, that is dipped in water, and then dries and stiffens by the contact with air. It is of utmost importance that these materials during manufacturing, packing, storage and distribution are not exposed to air or water, which makes them rather complicated to handle and sets high requirements to the whole manufacturing, storage and distribution chain.

Furthermore, this also limits the shelf-life of the product, which also makes the end product expensive. Furthermore, if the sealed air tight packaging of these products during the storage or handling is broken before time, the resin will start curing and stiffen, and the casting material will no longer be useable. In addition, if the material during the hardening does not achieve the right form and fit due to for instance too slow application or mal-positioning or move- ment of wearer, the splint often is not re-mouldable as it sets permanently. The use of fibreglass in casting and splinting materials have some drawbacks. The polymerising material in the fibreglass can cause skin allergic reactions, and it is therefore necessary to use gloves for the application and protect the patients skin by stockinette and padding. Fibreglass casts are water resistant, but water should not reach the padding inside. Damp padding is not easy to dry and can cause skin irritation. Furthermore, waste management of fibreglass is ecological difficult. The use of plaster casts has the drawbacks that the plaster is heavy and it may take up to one day to harden completely. Furthermore, plaster casts must be kept dry, otherwise they loose their stability. In general, it is also known to incorporate thermo- setting materials in orthopaedic products, however, the thermosetting materials suffer from the same drawbacks as mentioned above as they set permanently when heated. Based on the above mentioned drawbacks and disadvantages with different kinds of existing orthopaedic products, there is a need to develop and provide an all-in- one spacer fabric, in which several different properties such as skin friendliness, cushioning, moisture handling properties and breathability may still be incorporated, and wherein the spacer fabric is flexible and soft before subsequent heating treatments that enable stiffening of at least part of the surfaces of the spacer fabric or orthopaedic product, without significantly loosing the said properties . There is also a need for providing a stiffening spacer fabric with different levels of stiffness, which may be mouldable, re-mouldable, light-weight, durable, can handle exposure to water and are washable.

Summary of the Invention An object of the present invention is to wholly or partly overcome the above disadvantages and drawbacks of the prior art. More specifically, it is an object to provide a spacer fabric having at least a skin friendly inner surface, cushioning properties, and having built-in stiffening properties. It is also an object of the present invention to provide a spacer fabric which is soft and flexible before a heating treatment, to allow for easy processability, joining, handling and/or application. Another object of the present invention is to provide a spacer fabric, wherein at least part of one of the outer layers may be stiffened. A further object of the present invention is to pro- vide a spacer fabric which may easily be used and incorporated in orthopaedic products, with the involvement of few individual parts, and may be without additional rigid parts . It is moreover an object of the present invention to provide a spacer fabric having permeable properties such as breathability and good moisture handling properties, such as moisture permeability, moisture transportation, moisture resistance, quick drying and good washability. An additional object of the present invention is to provide a spacer fabric which in a cost-effective manner may be used to produce orthopaedic products, including sports bracing and sports goods equipment. It is moreover an object of the present invention to provide a spacer fabric which after stiffening may be re- moulded or in other ways shaped by a subsequent heating treatment, allowing an orthopaedic product to be moulded in an industrial environment, at the caregiver or ^Λin situ" . The above objects, together with numerous other ob- jects, advantages and features, which will become evident from the below description, are accomplished by a solution in accordance with the present invention by at least part of one of the outer layers of the spacer fabric comprising hybrid yarns, said hybrid yarns comprising at least one type of thermoplastic melting fibre, which in the following is referred to as the melting fibre, and at least one type of structural fibre, said fibres having different temperature profiles, wherein the thermoplastic fibre is adapted to melt, wet out and stiffen the fabric structure, at a temperature at which the structural fibre remains substantially unaffected, and subsequently be moulded or in other ways shaped. Hereby a spacer fabric is achieved having cushioning properties that due to the fact that the hybrid yarns before stiffening are "soft" and drapeable may be produced by conventional knitting or woven techniques. The spacer fabric may thus be processed as normal soft fabric having the same elasticity and flexibility. Furthermore, a spacer fabric is obtained that may stiffen at least in part of the area, wherein the hybrid yarn is incorporated after a subsequent heating treatment . The matter is that during the heating treatment of at least part of the area of the spacer fabric comprising the hybrid yarns, the melting fibres melt at a lower temperature than the structural fibre, whereby the melted fibres wet out and surround the structural fibre and when cooled (so-called consolidation) , form a so-called matrix material, which stiffens the said surface of the spacer fabric. Thus the stiffened surface of the spacer fabric will maintain its fabric structure due to the incorporated structural fibres and will furthermore become rigid or semi-rigid and achieve a certain stiffness, in the area where the matrix material was formed. Additionally, it is obtained that several properties may be built-in in the spacer fabric. The term "hybrid yarn" is in this context to be con- strued as being yarn made by combining at least two different fibre materials, closely commingled. The term "structural fibre" is in this context to be construed as being fibres that substantially maintain their structure and properties during and after a heating treatment. The term "temperature profile" is in this context to be construed as the thermal behaviour of a material, i.e. the temperature range, wherein the material significantly changes its properties, such as for instance the softening and melting range. Advantageously, the melting fibre may at least comprise a modified thermoplastic fibre with a low softening and melting temperature range. In a preferred embodiment according to the invention, the composition of the hybrid yarns may comprise 30-98% by weight melting fibres and 2-70% structural fibres . According to the invention, the melting fibre may be made of thermoplastic materials such as modified or unmodified polyester, polyamide, polypropylene, polyethylene, polyurethane, polyvinylchlorid or rubber based materials . The structural fibre may be inorganic such as glass fibres, carbon fibre, basalt, or organic fibres with thermoplastic properties with a higher melting range than the melting fibres, or natural or regenerated fibres such as cotton, or viscose. Common for these fibres are that they are substantially not affected by heat treatment at the temperature, at which the melting fibres melt. In case the structural fibres are thermoplastic, they should preferably have a melting range at least 20-30°C higher than the melting fibre. In an expedient embodiment according to the invention, the hybrid yarns may have a yarn count from 20 dtex to 4000 tex, preferably from 50 dtex to 2000 dtex. Advantageously the hybrid yarns may comprise filament fibres or stable fibres, formed into texturized, flat or spun yarn. According to the invention the melting fibres may start to soften and may be shapeable and/or re-mouldable at a temperature of 40-200°C, preferably of 70-90°C. By using melting fibres having a softening temperature of 70-90°C it is obtained that the spacer fabric may be shaped at a temperature which for example can be handled close to the human body, either directly or by using a thin, isolating layer between the skin and the spacer fabric, during the moulding process. In a preferred embodiment according to the invention the outer layer comprising stiffened knitted matrix mate- rial, may have a Shore-A-hardness of more than 85 (DIN 53505), preferably a Shore-D-hardness of more than 50. In an expedient manner both outer layers of the spacer fabric may fully or partly comprise hybrid yarns. According to the invention at least one of the outer layers may comprise other yarns having a yarn count of 50 dtex to 2000 dtex. Advantageously the other yarns may further comprise Elastane, polyester, polyamide, wool, cotton or viscose or a combination thereof, depending on the properties to be achieved,, i.e. skin friendliness, softness and moisture handling. The intermediate spacer layer ^'according to the invention may comprise monofilament or/and spun or other filament yarns having a yarn of 20 dtex to 2000 dtex. Expediently the pile yarns of the intermediate spacer layer may comprise polyester, polyamide, wool, cotton or viscose or a combination thereof, depending on the properties to be achieved, i.e. cushioning, softness and moisture handling. According to a preferred embodiment of the invention the spacer fabric may comprises at least one of the properties skin friendliness, softness, cushioning, elasticity, breathability, moisture handling, thermal properties such as cooling, warming, isolating, or a combination thereof. Furthermore, the outer layer comprising stiffened matrix material may have built-in loop properties, so- called Velcro- or hook-compatibility. This is obtained by a combination of hybrid yarn type and thickness, knitting structure, knitting tightness and subsequent heat treatment that allows the stiffened knitted surface to be still open or perforated to a certain degree, which in addition to the breathability properties gives a stiff- ened surface which may engage with hook closure means, and which due to the fixated structure advantageously will not be destroyed when the hook/loop closure is detached. Said hook/loop closure means have been adapted to mount the orthopaedic product on the wearers body part, and to adjust the size of the orthopaedic product. Also according to the invention at least one of the outer layers may be laminated with other materials, e.g. with another layer of textile comprising hybrid yarn, to enhance or modify the fabrics properties. In addition, two or more spacer fabrics may be laminated together, i.e. by stacking two spacer fabrics with the stiffening surfaces against each other during a heating treatment, which will make the stiffened surfaces stick together, and thereby form an intermediate stiff- ened layer incorporated between cushioning and soft layers on both sides. This provides a sandwich construction which have the stiff layers hidden between soft, skin friendly, breathable and cushioning layers. Said sandwich construction being used for orthopaedic products, being soft and cushioning on both sides, and still with stiffening and/or shapeable properties. Advantageously the sticking properties of the melt- ing fibres during heat treatment can be further utilized, for instance to seal the edges of the fabric. Furthermore, i.e. by bending the edges of a cut fabric piece to the melting side during heat treatment, the melting surface will stick to itself and keep the edges securely fixated afterwards, which may make further trimming or covering of the edges unnecessary. Said method being utilized in manufacturing of orthopaedic products, having soft, cushioning edges without additional trimming, even in rigid areas. Furthermore, the sticking properties of the melting fibres during heat treatment may be utilized in melt-gluing a piece of spacer fabric to other cut pieces of spacer fabric or other materials. This provides an easy and inexpensive assembly of anatomically shaped orthopaedic products, without additional seams. Advantageously according to the invention the spacer fabric may be adapted to be stiffened and/or shaped during one or more heating treatments. In an expedient embodiment according to the invention the melting fibres may melt, wet out and afterwards stiffen at a temperature of 180-300°C, and thus form a matrix material around the structural fibres. By first making such a high temperature consolidation of the thermoplastic material, a good dimensional stability of the matrix material is obtained, and any shrinkage tendency in the material is substantially removed. This allows for a subsequent reheating, i.e. shaping or moulding of the material without any shrinkage problems. In a further embodiment of the invention, the hybrid yarn or the outer surface of the spacer fabric containing hybrid yarn, may further comprise electrically leading materials such as carbon fibres, metal threads or coils or the like. A knitted-in grid of such fibres or threads in the spacer fabric may permit a heating and subsequent forming of the matrix material, by introducing energy from e.g. a battery or a power supply. In some instances, such a heating, stiffening and/or shaping method of or- thopaedic products may be preferred for example where there is no access to a heat gun or hot water. Depending on the product and the type of heat treatment, the heating treatment resulting in stiffening of the surface may be performed at different levels of the manufacturing chain, i.e. in the manufacturing environment, before or after cutting of the spacer fabric, before, intermediately or after forming the orthopaedic product, as last step of the manufacturing process, by the caregiver in a clinical environment or in situ, by the trainer in a sports environment or in some cases even by the end-user.

Brief Description of the Drawings The invention and its many advantages will be de- scribed in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments and in which Fig. 1 shows a part of the spacer fabric according to the invention in perspective, Fig. 2 shows a cross-sectional view taken by line A- A of the spacer fabric shown in Fig. 1, Fig. 3 shows a knitted surface structure of a spacer fabric comprising hybrid yarns according to the invention, Fig. 4 shows a cross-sectional view of a sandwich construction of two spacer fabrics laminated together according to the invention, and Fig. 5 shows a test apparatus in which the rigidity of the stiffened spacer fabric according to the invention is measured. All the figures are highly schematic and not necessarily to scale, and they show only parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.

Description of Preferred Embodiments The knitted spacer fabric 1 according to the invention is shown schematic in Fig. 1. The spacer fabric 1 comprises a first outer layer 2, a second outer layer 3, and an intermediate spacer layer 4 interknitted with said first 2 and second outer layer 3. The intermediate spacer layer 4 comprises monofila- ment or other yarns having a yarn count of 20 dtex to 2000 dtex and is interknitted with the outer layers 2; 3. The intermediate spacer layer 4 is arranged to provide the cushioning effect to the spacer fabric 1. The yarns of the spacer layer 4 are interknitted in the spacer fabric 1 so as to provide a fixation of the two outer layers 2; 3 in relation to each other thus obtaining a high shear stress of the spacer fabric. Furthermore, the intermedi- ate spacer 4 layer confer high compression resistance to the spacer fabric 1. According to the invention the density of the pile yarns in the intermediate spacer layer 4 may be from 10 to 800 ends per square cm. Furthermore, the pile yarns according to the knitting method may be arranged so as to provide an X or V-shape, when shown in a cross-sectional view as for instance in Fig. 2. Preferably, the pile yarns are arranged in this X or V-shaped formation so as to achieve a so-called lattice structure of the intermediate spacer layer 4 and thereby improving the resistance against collapsing when exerted with compressive forces. The pile yarns of the intermediate spacer layer 4 may comprise polyester, polyamide or polypropylene, cotton, wool, viscose or a combination thereof. According to the inventive idea at least part^' of one of the outer layers 2, 3 comprises hybrid yarns (not shown) , said hybrid yarns comprising at least one type of thermoplastic fibre the so-called melting fibre and at least one type of structural fibre. In Fig. 1 the area 5 on the outer layer 2 represents the part which comprises hybrid yarns. According to the invention the entire outer layer 2 may comprise hybrid yarns as well' as both outer layers 2, 3. The hybrid yarns may also be only in certain areas of the surface (s), such as in a stripy structure, in jacquard patterns etc. Said fibres are furthermore having different temperature profiles, wherein the melting fibre is adapted to melt, wet out and stiffen at a temperature, at which the structural fibre substantially remains unaffected. The hybrid yarns according to the invention may be a commingled texturized or spun yarn consisting of well mixed structural fibres and melting fibres. After the fabric forming operation, and in a subsequent heating process the thermoplastic fibres melt, wet out and form the matrix material in the formed fibre composite mate- rial, with the structural fibres as a built-in scaffold, in the following referred to as matrix material. Preferably the composition of the hybrid yarns may comprise 30-98% melting fibre and 2-70% structural fibre, wherein the melting fibre is made of thermoplastic materials such as modified or unmodified polyester, polyamide polyethylene, polyurethane, polyvinylchlorid, rubber or polypropylene based materials and wherein the structural fibre is made of more temperature resistant inorganic fi- bres, such as glass fibres, carbon fibre, basalt, or organic fibres, with thermoplastic properties or natural or regenerated fibres such as cotton, viscose or wool. The mentioned composition of the hybrid yarns have shown remarkable results in relation to obtaining that knitted stiffened layer may have a Shore-A-hardness of more than 85 (DIN 53505) , preferably a Shore-D-hardness of more than 40. Advantageously, the hybrid yarns may have a yarn count from 20 dtex to 4000 tex, preferably from 50 dtex to 2000 dtex, and the hybrid yarns may furthermore consist of filament or spun yarns. Preferably, at least one of the outer layers may further comprise yarns having a yarn count of 50 dtex to 2000 dtex. Advantageously, the other yarns of the outer layers may comprise Elastane, polyester, polyamide, wool, cotton or viscose or a combination thereof so as provide surfaces to the spacer fabric 1 which have the desired elasticity, breathability, moisture transportation properties, softness and other skin friendly properties. According to the invention the melting fibre may soften and be shapeable at a temperature of 40-200°C, preferably between 70-90°C, whereby it is obtained that the spacer fabric may be formed or moulded directly on or close to the wearer. Heating and subsequent forming of the matrix- material making at least part of the spacer fabric rigid or stiff, may be done by e.g. using a heat gun, using infra-red or near infra-red heat, using an oven or microwave-oven or in other conventional ways of heating or even attaching power to electrically leading fibres or threads . Furthermore, the melting fibres may melt and thus be fixated at a temperature between 200-280°C. This temperature range comprises the melting range of the preferred low temperature thermoplastic fibres. By first making such a high temperature fixation of the matrix material, a good dimensional stability of the matrix material is obtained, and any shrinkage tendency in the material is substantially removed. This allows for a subsequent reheating, i.e. shaping of the material without any shrinkage problems . Preferably, the processing temperature of the thermoplastic melting fibre does not overlap the melting range of the structural fibre. The difference should preferably be minimum 20-30°C. As shown schematically in Fig. 1 the edge 6 of the outer layer 3 may be bent around the intermediate layer 4 and up to the outer layer 2 during a heating treatment so that the sticking properties of the melting fibres are utilized, for instance, to seal the edges of the fabric 1. The matter is that by bending the edge 6 of a cut fab- ric piece to the melting side during heat treatment, the melting surface will stick to itself and keep the edge securely fixated afterwards, which may make further trimming or covering of the edges unnecessary. Said method being utilized in manufacturing of orthopaedic products, having soft, cushioning edges without additional trimming, even in rigid areas. As mentioned above Fig. 2 shows a schematic cross- sectional view taken along line A-A of the elastic spacer fabric shown in Fig. 1. By this cross-sectional view the lattice structure of the pile yarns of the intermediate spacer layer 4 is shown. The thickness of the spacer fabric 1 may be from 1 mm to 7 mm, preferably from 3 mm to 5 mm. However, the thickness may also be as high as 10 mm to 20 mm for certain applications, though, the thickness from 2 mm to 5 mm is most useful when the spacer fabric is to be incorporated into and used for orthopaedic products. According to the invention the spacer fabric 1 is produced preferably via the warp or weft knitting techniques for instance on a double needle bar raschel machine or on a circular knitting machine or flat knitting machine, and may also be woven, which techniques are all well known in the art. In Fig. 3 an enlarged view is shown illustrating a weft-knitted surface structure of a spacer fabric comprising hybrid yarns according to the invention. Furthermore, Fig. 3 shows an example of the wales and courses (the knitting structure) of the weft-knitted surface structure. In this embodiment, the black yarns 7 may for instance represent a hybrid yarn according to the invention and the white yarns 8 may represent other yarns for in- stance made of Elastane, polyester, polyamide, wool, cotton, polypropylene, or viscose or a combination thereof. Or both 7 and 8 may represent hybrid yarns. Fig. 4 shows a cross-sectional view of a sandwich construction 11 of two spacer fabrics laminated together according to the invention. Fig. 4 shows that two spacer fabrics are stacked with the stiffening surfaces against each other. During a -heating treatment, which will make the stiffened surfaces stick together, and thereby form an intermediate stiffened layer 9 incorporated between cushioning and soft layers 10 on both sides. This provides a sandwich construction 11 which has the stiff lay- ers 9 hidden between soft, skin friendly, breathable and cushioning layers 10. Said sandwich construction 11 expediently being used for orthopaedic products, being soft and cushioning on both sides, and still with stiffening and/or shapeable properties. Tests of the rigidity of the stiffened outer layer of a spacer fabric have been carried out using the following test method in which the apparatus schematically shown in Fig. 5 is used. The specimens b used were 75 mm long and 50 mm wide. Said specimens b were centred on two supporting poles having a distance a measured between the centre of the two poles. During the testing the distance a was set to 50 mm. After the specimen b were centred on the 'poles, a load device was arranged to apply a load from above, in the centre between the two poles on the specimen b as shown in Fig. 5. Said load device having a diameter c, set to be 12 mm and being substantially flat at the end facing the specimen b. During the applying of the load the force P as well as the deflection d of the specimen b between the poles were continuously measured. Said test showed that at least a force of above 10

N, preferably of above 20 N, most preferably of above 50 N should be applied to the specimen b of the stiffened spacer fabric 1 according to the invention in order to achieve a 10 mm deflection of said specimen b between the poles, irrespective of which direction the load is applied to the specimen, i.e. applied to the stiffened or soft side of the specimen or applied to the longitudinal or the breadth direction of the specimen. According to the invention the spacer fabric may be used for products for orthopaedic purposes such as orthopaedic splinting, orthopaedic casting, orthopaedic bracing, orthopaedic soft goods and support, for preventive as well as for treatment purposes. The spacer fabric may furthermore be used for podiatry such as foot orthotics or insoles or even for protective or preventive sports wear and sporting equipment, for athletic injury prevention. By the invention it is thereby achieved that several properties such as rigid, cushioning, soft, skin friendly, moisture handling and light-weight, may be produced in one spacer fabric. By the inventive spacer fabric it is furthermore achieved that it is possible to easily process the soft spacer fabric in all manufactur- ing operations and make it rigid/stiff as the last manufacturing step or even at the caregiver, and subsequently moulding or in other ways shaping the end product. Additionally it is obtained that it is possible to make only a part of the outer layers rigid and let others remain soft. It is further achieved by the invention that the stiffened ^'outer layer has a good breathability. Although the invention above has been described in connection with preferred embodiments of the invention, it will be evident for a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims.

Claims

1. A spacer fabric (1) having cushioning properties comprising a first outer layer (2), a second outer layer (3), and an intermediate spacer layer (4) integrated with said first (2) and second (3) outer layer, characterised in that at least part of one of the outer layers (2; 3) comprises hybrid yarns, said hybrid yarns comprising at least one type of thermoplastic melting fibre and at least one type of structural fibre, said fibres having different temperature profiles, wherein the thermoplastic fibre is adapted to melt, wet out and stiffen the fabric structure at a temperature, at which the structural fibre remains substantially unaffected, and subsequently be moulded or in other ways shaped.

2. A spacer fabric according to claim 1, wherein the melting fibre at least comprises a modified thermoplastic fibre with a low softening and melting temperature range.

3. A spacer fabric according to claim 2, wherein the composition of the hybrid yarns comprises 30-98% melting fibre and 2-70% structural fibre.

4. A spacer fabric according to claim 1, wherein the melting fibre is made of thermoplastic materials such as modified or unmodified polyester, polyamide, polypropylene, polyethylene, polyurethane, polyvinylchlorid or rubber based materials.

5. A spacer fabric according to claim 1, wherein the structural fibre is made of inorganic fibres, such as glass fibres, carbon fibre, basalt, or organic fibres, with thermoplastic properties with a higher melting range than the melting fibre, or natural or regenerated fibres such as, cotton, wool or viscose.

6. A spacer fabric according to claim 1, wherein the hybrid yarns are having a yarn count from 20 dtex to 4000 tex, preferably from 50 dtex to 2000 dtex.

7. A spacer fabric according to claim 1 or 6, wherein the hybrid yarns comprise filament fibres or stable fibres, formed into texturized, flat or spun yarn.

8. A spacer fabric according to claim 1, wherein the melting fibre starts to soften and is shapeable at a tem- perature of 40-200°C, preferably at 70-90°C.

9. A spacer fabric according to claim 1, wherein the outer layer comprising the stiffened structure has a Shore-A-hardness of more than 85 (DIN 53505) , preferably a Shore-D-hardness of more than 50.

10. A spacer fabric according to any of the preceding claims, wherein both outer layers (2, 3) fully or partly comprises hybrid yarns.

• 11. A spacer fabric according to any of the preceding claims, wherein the spacer fabric comprises at least one of the properties cushioning, elasticity, breathability, moisture handling properties, thermal properties or a combination thereof.

12. A spacer fabric according to any of the preceding claims, wherein the area comprising stiffened knitting structure has built-in hook-compatibility.

13. A spacer fabric according to any of the preceding claims, wherein at least one of the other layers (2, 3) are being laminated, to introduce further properties or enhance the properties of the fabric.

14. A spacer fabric according to any of the preceding claims, wherein the hybrid yarn or the area containing hybrid yarn, further comprises electrically leading materials, such as metal threads or coils or carbon fibre.

15. A spacer fabric according to any of the preceding claims, wherein the spacer fabric is sandwiched into a two layer-construction (11) , with the stiffening sides melt-glued together as the hidden intermediate layer.

16. A spacer fabric according to any of the preceding claims, wherein the edges (6) are bent towards the stiffening side, and thereby fixed, forming soft and cushioning edges.

17. A spacer fabric according to any of the preceding claims, wherein the spacer fabric is adapted to be stiffened and/or shaped during one or more heating treatments,

18. A spacer fabric according to any of the preceding claims, wherein the low melting fibres are melted, wet out and afterwards consolidated at a temperature between 180-300°C, preferably between 180-240°C.

19. Use of a spacer fabric according to claim 1-18 in products for orthopaedic purposes such as orthopaedic splinting, orthopaedic casting, orthopaedic bracing, orthopaedic soft goods and support, for preventive as well as for treatment purposes or for protective or preventive sports wear and/or sporting goods equipment and/or work wear.