Patent Publication Number: US-2023160113-A1

Title: Multilayer weft-knitted fabrics for mattress covers

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation-in-Part of U.S. application Ser. No. 15/778,825, filed May 24, 2018, which is a National Stage Application of International Application No. PCT/DE2016/100548, filed Nov. 24, 20216, which is based upon and claims the benefit of priority under German Patent Application No. 20 2015 008 053.7, filed Nov. 24, 2015, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     The invention relates to a mattress cover that comprises an upper face (top face) and a lower face (bottom face) and is intended to receive a mattress core. 
     Mattress covers that are generally known in practice are usually intended to tightly encase a rectangular mattress core, the upper face and lower face of which have a length and a width that are large compared with the height and form a lying surface for a person. 
     The mattress cover generally consists of a fabric region that forms the upper face and a fabric region that forms the lower face. In the case of a removable mattress cover that allows the mattress core to be inserted into the mattress cover or allows the mattress cover to be removed from the mattress core, a fastener, for example in the form of a zip fastener, is provided for this purpose, which fastener extends at least in part on the longitudinal sides and on the transverse sides when put onto the mattress core. 
     Depending on the embodiment of the mattress cover, the fabric regions of the upper face and lower face may be formed by individual fabric panels that form the relevant lying surface or the lower face and which are interconnected by fabric strips that form longitudinal sides and the transverse sides. Fabric strips of this kind are generally connected to the fabric panels of the upper face and lower face by means of stitched seams, it being possible for the stitched seams to be covered by an edge binding or a welting band. 
     In the case of mattress covers known in practice, ventilation strips consisting of a material that is highly permeable compared with the further mattress cover fabric are in addition often used on the longitudinal sides and transverse sides, since usual cover fabrics for a mattress cover usually have a low degree of air permeability and the mattress core is otherwise inadequately ventilated. 
     DE 10 2008 058 134 83 B3 for example discloses using warp-knitted three-dimensional spacer fabrics as the highly air-permeable material for a ventilation strip of this kind, which warp-knitted spacer fabrics have a high degree of air permeability while having relatively good stability. 
     DE 20 2012 005 880 U1 furthermore discloses designing a mattress cover in two parts, such that one side is formed of a viscoelastic foam, as a winter cover, and the other side is formed of warp-knitted 3D spacer fabrics, as a summer cover which, on account of the greater breathability thereof, produces a better microclimate for the sleeper. 
     A disadvantage in this case, however, is that warp-knitted 3D spacer fabrics are relatively stiff and inflexible, which restricts the design of the lying comfort for the sleeper. 
     DE 202 01 919 U1 discloses the use of a weft-knitted spacer fabric for mattress and seat covers, as well as linings having outside and inside textiles surfaces that consist of a textile that has been shrunk in a washing process, and a spacer structure therebetween, the spacing threads of which are formed, on the mutually facing inner surfaces, by knitted monofilament or multifilament threads, one or both of the external surfaces being provided with a jacquard pattern. 
     On account of the different structure thereof, weft-knitted spacer fabrics are more stretchable than warp-knitted spacer fabrics, with the result that a mattress cover formed having a weft-knitted spacer fabric makes it possible, in principle, to increase the comfort for a user, since said mattress cover can be formed so as to be soft, springy and to have a pleasant feel. 
     It has been found in practice, however, that there is a need to improve the known weft-knitted spacer fabrics with respect to the breathability and the lying comfort. 
     SUMMARY 
     An object of the present invention may therefore be to provide for a mattress cover of the type mentioned at the outset, which cover is particularly breathable, forms a comfortable and soft lying surface, and allows for simple workability. 
     This object is achieved, according to the invention, by a mattress cover comprising a cover fabric that forms an upper face and/or a lower face that are each dimensioned as a lying surface for a user, in that the cover fabric is formed having a weft-knitted 3D (three-dimensional) spacer fabric at least on the outer face thereof and comprises a honeycombed mesh structure having outwardly open recesses on the outer face thereof. 
     The invention therefore makes use of the advantages of a weft-knitted spacer fabric which typically comprises a spacer structure having stitches of knitted monofilament or multifilament threads, and combines said advantages with the advantages of a honeycombed mesh structure that allows particularly efficient air circulation and moisture removal from the mattress. 
     In this case, however, the honeycombed, outwardly open recesses are advantageous not only with respect to air exchange and moisture removal as well as compensation of temperature fluctuations in general, but also allow for increased springiness which provides a user with a soft feel and in addition allows the mattress cover to be optimally adapted to the user lying thereon without said user being disturbed in the process by coarse spacing threads that are often noticeable in weft-knitted spacer fabrics. 
     A mattress cover of this kind can be produced in a simple manner, for example on a large circular knitting machine operating in accordance with a 3-way technique, at a high throughput over time and thus very economically. 
     In this case, the recesses of the mesh structure are preferably provided so as to be in a regular arrangement on the outer face of the cover fabric, an irregular arrangement, for example forming a pattern, also being conceivable, however. 
     The honeycombed, outwardly open recesses may be variable in terms of the geometry thereof, and thus the open cross section thereof may be round or oval or angular for example. 
     In a preferred embodiment of the invention, the cover fabric consisting of weft-knitted 3D spacer fabric is formed in at least two layers, having an upper layer that forms the outer face, and a preferably polyester fibrous material woven fabric layer that forms an inner layer. 
     In this case, the inner layer forms a smooth woven fabric layer, for example a layer of non-textured polyester yarn, which may optionally be jacquarded and provided with a pattern for example, and on which woven fabric layer the upper layer of the weft-knitted 3D spacer fabric made of textured, optionally twisted yarn, in particular multifilament yarn, is built up outwardly. 
     The outwardly open recesses may refer to openings or free-areas formed in at least the upper layer, and optionally also in one or more middle layers of the cover fabric. Each of the outwardly open recesses may comprise an open cross-section of substantially round or rounded shape, wherein the open-cross-section of the recesses may be defined in a plane of the upper layer, and optionally in one or more planes defined by one or more middle layers. Exemplary geometries of the open cross-section may be round, elliptical, or oval. 
     Alternatively or additionally, each of the outwardly open recesses may extend from the outer face of the mattress cover through the upper layer or through a thickness of the upper layer, for example a thickness measured along or parallel to a surface normal vector of the outer face, adjoining the inner layer of the cover fabric. Optionally, each of the outwardly open recesses may extend from the outer face of the mattress cover through the upper layer and through one or more middle layers of the cover fabric, adjoining the inner layer of the cover fabric. 
     Alternatively or additionally, each of the outwardly open recesses may be surrounded along a circumference of the respective recess and/or its open cross-section or cross-sectional area, in particular along the whole circumference of the respective recess, by material or fabric of the upper layer, for example by knitted or weft-knitted material or fabric of the upper layer, and optionally by material or fabric, for example knitted or weft-knitted material or fabric, of one or more middle layers of the cover fabric. Accordingly, each of the outwardly open recesses in the upper layer may be defined by a knitted fabric or material of the upper layer, which may be knitted or weft-knitted around the respective recess in the upper layer. Alternatively or additionally, each of the outwardly open recesses in one or more middle layers of the cover fabric may be defined by a knitted fabric or material of the one or more middle layers, which may be knitted or weft-knitted around the respective recess. Accordingly, each of the outwardly open recesses may be surrounded by a plurality of stitches of the upper layer, and optionally of one or more middle layers of the fabric. Accordingly, the outwardly open recesses may have a size or extension in one or more spatial directions, which is larger than a size or extension of a single stitch of the upper layer and/or the one or more middle layers in said one or more spatial directions. For instance, the size of a recess may be at least two times to at least ten times larger than the size of a single stitch of the cover fabric. 
     In an exemplary embodiment, a cross-sectional area of each of the recesses may be substantially identical in the upper layer and in one or more middle layers. Accordingly, a cross-sectional area of each recess may be constant along a direction parallel to a surface normal vector of the outer face, for example along an orthogonal or vertical direction from the upper layer or outer face of the cover fabric towards the inner layer of the cover fabric. 
     Alternatively, a cross-sectional area of each recess may be larger in the upper layer compared to the cross-sectional area of the corresponding recess in one or more middle layers of the cover fabric. For example, the recesses may extend in a V-shape, U-shape, a cylindrical shape, a conical shape, or a triangular shape from the upper layer of the cover fabric, optionally through one or more middle layers of the cover fabric, and towards or to the inner layer, wherein the cross-section or cross-sectional area of each recess may decrease from the upper layer towards the inner layer of the cover fabric. 
     Alternatively or additionally, adjacent or neighbouring recesses in the upper layer, and optionally in one or more middle layers, may be separated from one another by material or fabric of the upper layer, and optionally of the one or more middle layers. 
     The inner layer of the cover fabric may be or form a continuous layer of woven fabric, such as for example knitted or weft-knitted material. Accordingly, the inner layer may form a closed surface of the cover fabric, for example which may not comprise outwardly open recesses. In other words, the inner layer may be recess-free or a substantially smooth layer of fabric or material, for example knitted or weft-knitted fabric or material. Further, each of the recesses may have an open end formed at and/or defined by the outer face and/or the upper layer, and a further end of each recess, which opposes the respective open end in a direction parallel to the surface normal vector and/or along the longitudinal direction of the recess, may be closed. The closed end of each recess may be formed and/or defined by the inner layer of the cover fabric. 
     In this case, the honeycombed recesses may extend at least substantially over the entire thickness of the upper layer, i.e. from the outer face as far as the inner layer or close thereto, in order to allow for optimum conditioning with regard to the air and moisture exchange between the two sides of the cover fabric. Moreover, the depth of the honeycombed recess increases the softness of the weft-knitted 3D spacer fabric upper layer, as a result of which an improved feel can be achieved. 
     If the cover fabric is formed in three layers, comprising a middle layer that is knitted to the upper layer and comprises a monofilament yarn as a filling material, stabilisation and volumisation (increase in volume) of the weft-knitted 3D spacer fabric, which volumisation is frequently desired in terms of feel, can be achieved at the same time as a high degree of air and moisture permeability. According to a preferred embodiment, the monofilament yarn may be formed of polyester, but other synthetic fibres, such as fibres formed of polyamide, are also possible therefor. 
     In order to provide the outwardly facing surface of the weft-knitted spacer fabric with a particularly smooth and pleasant feel, the surface surrounding the honeycombed recesses may be formed by particularly fine knitting stitches. 
     Tests have shown that it is particularly advantageous, with respect to comfort and micro-conditioning, for the upper layer of the weft-knitted spacer fabric to have a weight portion of cover fabric of from 50% to 70%, in particular from 55% to 60%. 
     In this case, the inner layer may have a weight portion of cover fabric of from 20% to 30%, in particular from 25% to 30%. 
     When a filling material is used, optimum results in terms of air permeability, stabilisation and volumisation were identified when the middle layer has a weight portion of cover fabric of from 10% to 20%, in particular from 15% to 20%. 
     In this case, the cover fabric may have a weight of from 200 g/m 2  to 300 g/m 2 , as a result of which it has the required durability and is at the same time easy to handle, in terms of the weight thereof, both during production and during use. 
     The mattress cover may be designed so as to be the same on all faces, i.e. on the upper face, on the lower face and on the longitudinal and transverse sides that are formed when a mattress core is inserted, it also being conceivable in principle, however, for different faces of the mattress cover to also be designed differently. 
     Designing all the faces so as to be the same allows for particularly efficient production, the high level of breathability of the cover fabric also making it possible to omit a ventilation band on the transverse and longitudinal sides, which band is often present in known mattress covers. 
     In order to allow a mattress core to be inserted and removed, it is advantageous for the mattress cover to comprise a fastener, in particular a zip fastener, that is peripheral at least in part. Furthermore, in order to make it easier to handle the mattress that is covered by the mattress cover, grips may be sewn onto the mattress cover. 
     Further advantages and advantageous developments of the invention can be found in the claims and in the embodiment that is described schematically and with reference to the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic perspective view of a mattress cover that is designed according to the invention and has been put onto a mattress core; 
         FIG.  2    is a highly simplified plan view of a detail of an outer face of the mattress cover; and 
         FIG.  3    is a schematic cross-sectional view through a region of a cover fabric of the mattress cover. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIG.  1   , a mattress cover  1  can be seen in a state when stretched over a mattress core  2 , the mattress cover  1  forming, for a user sleeping thereon, a first lying surface on an upper face  3  and a second lying surface on an opposing lower face  4 . 
     The mattress cover  1  is formed by the same cover fabric  5  all the way around, lateral transverse surfaces  6  and longitudinal surfaces  7  also transitioning seamlessly, in the present case, into the upper face  6  and lower face  7 . 
     Deviating therefrom, however, in other embodiments the surfaces of the cover fabric  5  may also be separated by stitched seams and a welting band may optionally also be provided. 
     In order to insert and remove the mattress core  2 , a peripheral fastener  8  in the form of a zip fastener is sewn into the mattress cover  1  on the transverse surfaces  6  and longitudinal sides  7 . In addition, a plurality of grips  9  for lifting the mattress core  2 , encompassed by the mattress cover  1 , are provided on the lateral longitudinal surfaces  7 , just one of said grips or handles  9  being shown by way of example. 
     As can be seen in a detail X in  FIG.  1   , which detail represents the entire surface of the mattress cover  1 , and in  FIG.  2    and  FIG.  3   , the cover fabric  5  is formed having a weft-knitted 3D spacer fabric  10  as far as the outer face  11  thereof, the cover fabric  5  having a honeycombed mesh structure having a regular, delicate arrangement of outwardly open recesses  12  or openings  12 . In this case, the recesses  12  preferably have an oval cross section towards the outside, which cross section can be approximately 2 mm to 4 mm wide and approximately 3 mm to 5 mm long when unstretched. The widths of the weft-knitted spacer fabric  10  material projections  13  located between the mutually offset and regular recesses  12  are at least approximately the same. 
     In the example shown in the figures, the cover fabric  5  of the mattress cover  1  is designed as a three-layer weft-knitted 3D spacer fabric comprising an upper layer  14  that forms the outer face  11  and is formed of a textured, twisted polyester multifilament yarn; a middle layer  15  that is made of a coarse polyester multifilament yarn, is knitted to the upper layer  14 , jointly forms the weft-knitted spacer fabric  10  and is used as a filling material; and a layer of smooth or non-textured polyester yarn that is knitted to the upper layer  14  and the middle layer  15  and forms an inner layer  16 . 
     In this case, the upper layer  14  has a finely knitted structure  17  on the outer face  11  thereof, which structure provides the surface with a soft feel. 
     Each of the outwardly open recesses  12  may extend from the outer face  11  of the mattress cover  1  through the upper layer  14  or through a thickness of the upper layer  14  and through the middle layer  15 , and each recess may adjoin the inner layer  16  of the cover fabric  5 . Further, each recess  12  may be surrounded along a circumference of the respective recess  12  and/or its open cross-section or cross-sectional area by material or fabric of the upper layer  14  and of one or more middle layers  15  of the cover fabric. Accordingly, each of the outwardly open recesses  12  may be surrounded by a plurality of stitches of the upper layer  14 , and the middle layer  15 . 
     For example, a cross-sectional area of each of the recesses  12  may be substantially identical in the upper layer  14  and in one or more middle layers  15 . Accordingly, a cross-sectional area of each recess  12  may be constant along a direction parallel to a surface normal vector of the outer face  11 , for example along an orthogonal or vertical direction from the upper layer  14  or outer face  11  of the cover fabric towards the inner layer  16  of the cover fabric  5 . Alternatively, a cross-sectional area of each recess  12  may be larger in the upper layer  14  compared to the cross-sectional area of the corresponding recess  12  in one or more middle layers  15  of the cover fabric  5 . For example, the recesses  12  may extend in a V-shape, U-shape, a cylindrical shape, a conical shape, or a triangular shape from the upper layer  14  of the cover fabric  5 , optionally through one or more middle layers  15  of the cover fabric  5 , and towards or to the inner layer  16 , wherein the cross-section or cross-sectional area of each recess  12  may decrease from the upper layer  14  towards the inner layer  16  of the cover fabric. 
     Adjacent or neighbouring recesses  12  in the upper layer  14 , and optionally in one or more middle layers  15 , may be separated from one another by material or fabric of the upper layer  14 , and optionally of the one or more middle layers  15 . 
     The inner layer  16  of the cover fabric  5  may be or form a continuous and/or recess-free layer of woven fabric or material, such as for example knitted or weft-knitted material or fabric. Accordingly, the inner layer  16  may form a closed surface of the cover fabric  5 , for example which may not comprise outwardly open recesses  12 . In other words, the inner layer  16  may be recess-free or a substantially smooth layer of fabric or material, for example knitted or weft-knitted fabric or material. Accordingly, the recesses  12  may only or solely be formed in the upper layer and optionally one or more middle layers  15 . 
     With regard to the thickness, in the advantageous embodiment shown, the upper layer  14  is dimensioned so as to occupy at least 70% to 80% of the total thickness of the cover fabric  5 , in order make use, as far as possible, of the microclimatic advantages of the weft-knitted spacer fabric  10 . 
     In order to allow as much air circulation as possible and optimal moisture removal at the outer face, the honeycombed recesses  12  extend substantially over the thickness of the upper layer  14  and of the middle layer  15  until adjacent to the lower layer  16  such that, as a result of the recesses  12 , the cover fabric is very flexible and stretchable in the width direction. The springiness in the height direction achieves a softness which can be defined, according to the desired degree of softness, by means of the filling material of the middle layer  14 . 
     Of course, depending on the application, the cover fabric  5  can be produced using all known methods for weft-knitting spacer fabrics on circular knitting machines, and using all known finishing methods, such as a washing, bleaching and shrinking process following the knitting process.