Patent Description:
Embodiments of the disclosure relate generally to cushioning elements such as mattresses and mattress toppers, fabrics for use with cushioning elements, products including cushioning elements, and to methods of making and using fabrics and cushioning elements.

Cushioning materials have a variety of uses, such as for mattresses, seating surfaces, shoe inserts, packaging, medical devices, etc. Cushioning materials may be formulated and/or configured to reduce peak pressure on a cushioned body, which may increase comfort for humans or animals, and may protect objects from damage. Cushioning materials may be formed of materials that deflect or deform under load, such as polyethylene or polyurethane foams (e.g., convoluted foam), vinyl, rubber, springs, natural or synthetic fibers, fluid-filled flexible containers, etc. Different cushioning materials may have different responses to a given pressure, and some materials may be well suited to different applications. Cushioning materials may be used in combination with one another to achieve selected properties.

<CIT>, describes cushion structures having interconnected walls that buckle. A first wall buckles when a threshold force is applied. Buckling of the first wall may cause buckling of a second wall, which may decrease die chance that the first wall will "bottom out. " Bottoming out would increase pressure on the portion of the cushioned object over the buckled portion of the cushion. One side of the cushion has walls spaced relatively close together, and the opposite side has walls spaced farther apart. That is, some walls of the cushion extend only partially through the cushion. The wider-spaced portions of the walls may buckle more easily than the closer-spaced portions of the walls when an irregularly shaped object presses against die walls.

<CIT>, describes a cushioning element having a top cushioning surface and a bottom base surface, which includes an elastomeric material and a stabilizing material. Interconnected buckling walls formed of the elastomeric material are connected to the stabilizing material.

When lying on a core that has a top surface (or a surface near the top, underneath a cover) of buckling walls formed of an elastomeric material, there may be a degree of discomfort or undesirable awareness associated with the buckling members of the elastomeric material. For example, if the buckling elastomer has square hollow columns (for example, as shown in <CIT>, discussed above, or in <CIT>), the user of the mattress or mattress topper may feel the squares on his or her skin, or may undesirably feel the buckling action. Generally, a top foam may be placed above the buckling elastomer, or a top-quilted set of fabrics and/or foams may be placed atop the buckling elastomer. This may completely or at least partially overcome the undesirable sensations. However, it may be expensive to put foam atop the buckling elastomer, which may involve multiple steps of cutting the foam, heat fusing a bondable fabric into the buckling elastomer, gluing the bondable fabric to the foam, etc. A top quilt may also be undesirable because of the cost of the various layers of quilted material (for example a typical quilt package may be a knitted top fabric, a foam, poly-fluff fiber, and a bottom piece of non-stretchable fabric, which may be generally necessary to pull the quilt through the quilting machine) and the cost and complexity of the quilting machine and process. A knitted cover for mattresses is known from <CIT>.

The invention provides a mattress topper and a method of forming a mattress or a mattress topper as claimed in claims <NUM> and <NUM>.

As used herein, the term "cushioning element" means and includes any deformable device intended for use in cushioning one body (e.g., a person, animal, or object) relative to another. As a non-limiting example, cushioning elements (e.g., mattresses, mattress toppers, seat cushions, etc.) include materials intended for use in cushioning a person, animal, or object relative to another object (e.g., a chair seat) that might otherwise abut against the person, animal or object.

As used herein, the term "elastomeric polymer" means and includes a polymer capable of recovering its original size and shape after deformation. In other words, an elastomeric polymer is a polymer having elastic or viscoelastic properties. Elastomeric polymers may also be referred to as "elastomers" in the art. Elastomeric polymers include, without limitation, homopolymers (polymers having a single chemical unit repeated) and copolymers (polymers having two or more chemical units).

As used herein, the term "elastomeric block copolymer" means and includes an elastomeric polymer having groups or blocks of homo polymers linked together, such as A-B diblock copolymers and A-B-A triblock copolymers. A-B diblock copolymers have two distinct blocks of homopolymers. A-B-A triblock copolymers have two blocks of a single homopolymer (A) each linked to a single block of a different homopolymer (B).

As used herein, the term "plasticizer" means and includes a substance added to another material (e.g., an elastomeric polymer) to increase a workability of the material. For example, a plasticizer may increase the flexibility, softness, or extensibility of the material. Plasticizers include, without limitation, hydrocarbon fluids, such as mineral oils. Hydrocarbon plasticizers may be aromatic or aliphatic.

As used herein, the term "elastomeric material" means and includes elastomeric polymers and mixtures of elastomeric polymers with plasticizers and/or other materials. Elastomeric materials are elastic (i.e., capable of recovering size and shape after deformation). Elastomeric materials include, without limitation, materials referred to in the art as "elastomer gels," "gelatinous elastomers," or simply "gels.

As used herein, the terms "stretchable" and "stretchable material" mean and include a fabric having the ability to stretch to at least <NUM>% of its undeformed length when pulled (i.e., may increase its length by at least <NUM>%), yet return to its original shape when released. "Two-way" stretchable material stretches in two opposite directions, whereas "four-way" stretchable material stretches in two mutually opposing directions plus two directions perpendicular to the two mutually opposing directions (i.e., in two directions perpendicular to one another and in each direction opposite each of these perpendicular directions).

As used herein, the terms "knitted" and "knit" mean and include a fabric formed by interlocking loops of threads or yams. Knitted fabrics are porous and stretchable even when formed of non-stretchable fibers, because the threads can shift within a matrix of loops.

The illustrations presented herein are not actual views of any particular material or device, but are merely idealized representations employed to describe embodiments of the present disclosure. Elements common between figures may retain the same numerical designation.

The present disclosure describes knitted fabric including multiple layers of stretchable material knitted together as a unitary sheet. The fabric can be of a relatively heavy gage having suitable bulk for providing some cushioning effect when used in conjunction with a mattress, mattress topper, or other cushioning device having buckling walls. The fabric may alleviate problems associated with placing foam layers or quilted layers over buckling walls. In particular, foam and quilted layers may each have relatively low stretchiness due to, for example, adhesives, stitching, or non-stretch fabric. This lack of sufficient stretchiness may inhibit the desirable buckling action, particularly local buckling around a protrusion such as a human hip, and thus a mattress or mattress topper of such materials may be less comfortable, have higher peak pressures on the user, and may have less ability to align the user's spine. A knitted fabric as disclosed herein may provide cushioning and be stretchable, such that buckling walls are less noticeable to a user.

<FIG> is a simplified cross-sectional view of a knitted fabric <NUM>, which includes a top layer <NUM>, a bottom layer <NUM>, and a fill material <NUM>. Though shown and described as "top" and "bottom" for simplicity and clarity, the top layer <NUM> and bottom layer <NUM> may be formed and used in any orientation, including inverted from the direction shown, rotated <NUM>°, etc. Each of the top layer <NUM>, bottom layer <NUM>, and fill material <NUM> is formed of a stretchable material, such that the overall fabric <NUM> remains stretchable. The top layer <NUM>, bottom layer <NUM>, and fill material <NUM> are knitted together as a single unitary sheet of fabric, such that no adhesive, stitching, or other attachment may be necessary to connect the top layer <NUM>, bottom layer <NUM>, and fill material <NUM> after knitting the fabric <NUM>. The fabric <NUM> may be substantially free of non-stretchable material.

To form the knitted fabric <NUM>, threads may be knitted to form the top layer <NUM> and bottom layer <NUM> simultaneously, encapsulating the fill material <NUM> as the top layer <NUM> and bottom layer <NUM> are formed. For example, a fiber or thread may be used to form a portion of die top layer <NUM>, then looped to form a portion of the bottom layer <NUM> (though the knitted fabric <NUM> may include more than one of such threads). The fill material <NUM> may be formed of threads selected for bulk or fluff. When the top layer <NUM> is looped with the bottom layer <NUM>, the fill material <NUM> may be encapsulated into the fabric. In some embodiments, a machine such as a circular knitting machine may form a portion of the top layer <NUM> (e.g., one or a few loops), then form a portion of the bottom layer <NUM>. The process may repeat to form the entire knitted fabric <NUM> as a unitary sheet.

The fabric <NUM> exhibits stretchiness in at least two directions perpendicular to one another, which in the industry may be referred to as "four-way stretch. " For example, the fabric <NUM> may stretch in each of two perpendicular directions in die plane of a surface of the fabric <NUM>, such that a force acting on the fabric <NUM> in any direction in the plane of the surface may cause the fabric <NUM> to stretch in that direction. To achieve such a property, the fabric <NUM> consists essentially or entirely of materials exhibiting stretchiness in at least two directions perpendicular to one another (e.g., in directions parallel to a surface of the fabric <NUM>). The fabric <NUM> may also stretch in a third perpendicular direction (e.g., perpendicular to a surface of the fabric <NUM>).

The stretchable material of the fabric <NUM> may include, for example, an elastomeric fiber. Elastomeric fibers, which may also be known in the art as "soft fibers," may stretch as much as <NUM>% or more while retaining the ability to return to their original shape. Elastomeric fibers include, for example, spandex (i.e., "a manufactured fiber in which the fiber-forming substance is a long chain synthetic polymer comprised of at least <NUM>% of a segmented polyurethane" (see <NUM> C. § <NUM>)), natural or synthetic rubber, olefins, polyesters, polyethers, etc., and combinations thereof. In some embodiments, the fabric <NUM> may include at least about <NUM>% elastomeric fiber by weight, such as from about <NUM>% to about <NUM>% elastomeric fiber by weight, or from about <NUM>% to about <NUM>% elastomeric fiber by weight.

In some embodiments, the fabric <NUM> may have a weight per unit area of at least about <NUM>/m<NUM>, at least about <NUM>/m<NUM>, or even at least about <NUM>/m<NUM>. The fabric <NUM> may have a bulk or maximum uncompressed thickness T of at least about <NUM>, at least about <NUM>, or at least about <NUM>. The weight and thickness of the fabric <NUM> may provide the fabric <NUM> with the ability to provide some cushioning effect.

The fabric <NUM> may have a varying thickness when uncompressed. For example, as shown in <FIG>, the fabric <NUM> may have relatively thicker sections <NUM> and relatively thinner sections <NUM>. The top layer <NUM> and the bottom layer <NUM> may be knitted together by interlocking loops of thread in the thinner sections <NUM> of the fabric <NUM>. The fabric <NUM> may be knitted such that die fill material <NUM> is thicker in the thicker sections <NUM> than in the thinner sections <NUM>, whereas the top layer <NUM> and bottom layer <NUM> may each be an approximately uniform thickness. The fabric <NUM> may be knitted to maintain the shape of the thicker sections <NUM> and thinner sections <NUM> to retain the fill material <NUM> in position. The fabric <NUM> may be shaped such that it has the appearance of a quilted fabric, yet may be a single, unitary sheet. Thus, manufacturing of the fabric <NUM> may be simpler and less expensive than quilting.

<FIG> illustrates how the fabric <NUM> may appear from above or below. The thinner sections <NUM> may generally form lines or curves in the surface of the fabric <NUM>, which may have the appearance of quilting stitches. The thinner sections <NUM> may be in any selected pattern for aesthetic or other purposes.

The fabric <NUM> may be configured to compress under a load, such that the fabric <NUM> may provide a cushioning effect. The fabric <NUM> may be used over a mattress or other cushion to improve cushioning properties of the mattress or cushion.

<FIG> is a simplified cross-sectional view illustrating a portion of a mattress or mattress topper <NUM> (hereinafter, "mattress <NUM>") including the fabric <NUM> and other cushioning elements. In particular, the fabric <NUM> is depicted resting over an elastomeric cushioning element <NUM>, which is over a foam base <NUM>. The fabric <NUM> may be configured to move independently of the elastomeric cushioning element <NUM> and the foam base <NUM>, and thus may not be bonded to the elastomeric cushioning element <NUM> along the interface between the fabric <NUM> and the elastomeric cushioning element <NUM>. Instead, the fabric <NUM> may be incorporated into a removable cover for the elastomeric cushioning element <NUM> and optionally the foam base <NUM>, and may be connected to the elastomeric cushioning element <NUM> at the edges of the elastomeric cushioning element <NUM>, such as by at least partially surrounding the elastomeric cushioning element <NUM>. Thus, the fabric <NUM> may freely move laterally with respect to the underlying elastomeric cushioning element <NUM>, at least along the interface therebetween. The fabric <NUM> may be removed for washing or replacement.

In some embodiments, another stretchable material <NUM> may be disposed between the fabric <NUM> and the elastomeric cushioning element <NUM>, such as a knitted flame-retardant fabric. The stretchable material <NUM> may be secured to or integral with either the fabric <NUM> or the elastomeric cushioning element <NUM>, but typically not to both, so as to allow the fabric <NUM> and the elastomeric cushioning element <NUM> to move freely relative to one another. In some embodiments, the stretchable material <NUM>, if present, may be distinct from both the fabric <NUM> and the elastomeric cushioning element <NUM>. The stretchable material <NUM> may be relatively thinner than the fabric <NUM>, such that the stretchable material <NUM> provides little or no cushioning effect to the mattress <NUM>. For example, the stretchable material <NUM> may have a thickness of less than about <NUM>, less than about <NUM>, or less than about <NUM>. In other embodiments, the fabric <NUM> may be in direct physical contact with the elastomeric cushioning element <NUM>, without any other material between the fabric <NUM> and the elastomeric cushioning element <NUM>.

The fabric <NUM> may have a bulk thickness T larger than conventional stretchable mattress covers. Conventional mattress covers are typically designed to protect a mattress from soiling and wear without constraining the mattress, but are not typically meant to provide cushioning themselves. Thus, conventional mattress covers are typically relatively thin, such as from about <NUM> to about <NUM> thick. Such thinner covers are typically selected because they weigh less and are less expensive to produce than thicker covers. However, it has unexpectedly been found that the fabric <NUM>, having a knit construction of flexible material with a thickness on die order at least about <NUM>, can provide a cushioning effect. When placed over, but not affixed to, an elastomeric cushioning element <NUM>, such a fabric <NUM> may alleviate pressure of individual cushioning features within the elastomeric cushioning element <NUM>. Furthermore, the fabric <NUM>, being formed as a single unitary sheet, may be less expensive to produce than multi-layered quilted fabrics, and may be formed without the use of a non-stretchable material layer typically required for quilting.

The elastomeric cushioning element <NUM> may include, for example, an elastomeric cushioning material as described in <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>.

<FIG> is a simplified top view of the elastomeric cushioning element <NUM>. The elastomeric cushioning element <NUM> includes intersecting buckling walls <NUM> that are interconnected and define hollow columns <NUM> or voids. Though the buckling walls <NUM> are depicted as intersecting at right angles, the buckling walls <NUM> may be in any selected configuration. For example, the buckling walls <NUM> may be configured to form triangular hollow columns <NUM>, hexagonal hollow columns <NUM>, skewed parallelogram hollow columns <NUM>, etc..

The elastomeric cushioning element <NUM> may have any selected dimensions based on the intended use. For example, if the mattress <NUM> is a mattress for a queen size bed, the elastomeric cushioning element <NUM> may be approximately <NUM> inches (<NUM>) by <NUM> inches (<NUM>), with a thickness of about <NUM> inches (<NUM>). In some embodiments, the thickness of the elastomeric cushioning element <NUM> may be between about <NUM> inch (<NUM>) and about <NUM> inches (<NUM>), such as from about <NUM> inches (<NUM>) to about δ inches (<NUM>). The thickness of the elastomeric cushioning element <NUM> may vary based on the thickness of other parts of the mattress <NUM>.

In some embodiments, the elastomeric cushioning element <NUM> may be configured to be used instead of a support core of springs or firm foam in a conventional mattress. To provide a mattress that may be easily lifted and maneuvered, the elastomeric cushioning element <NUM> may be configured to have a lower overall density than the fabric <NUM>. As used herein, the term "overall density" means and includes the mass of the elastomeric cushioning element <NUM> divided by the volume of the elastomeric cushioning element <NUM> as determined by its outside dimensions, including the volume of the interiors of the columns <NUM> in the elastomeric cushioning element <NUM>.

To keep the overall density of the elastomeric cushioning element <NUM> low, the volume of the interiors of the columns <NUM> may be increased, and the volume of the buckling walls <NUM> may be decreased. For example, the buckling walls <NUM> may be relatively thin in comparison with conventional cushioning elements. Similarly, the spaces between adjacent buckling walls <NUM> may be relatively wide in comparison with conventional cushioning elements. For example, the spaces between adjacent buckling walls <NUM> may be at least about <NUM> inch (<NUM>), at least about <NUM> inch (<NUM>), or even larger. In some embodiments, a ratio of the distance between adjacent buckling walls <NUM> to the thickness of the buckling walls <NUM> may be from about <NUM> to about <NUM>, such as from about <NUM> to about <NUM>, or from about <NUM> to about <NUM>. For example, an elastomeric cushioning element <NUM> may have buckling walls <NUM> with a thickness of about <NUM> inch (<NUM>) and a distance between adjacent buckling walls <NUM> of about <NUM> inch (<NUM>). In some embodiments, the elastomeric cushioning element <NUM> may have an overall density from about <NUM> lb/ft<NUM> (<NUM>/m<NUM>) to about <NUM> lb/ft<NUM> (<NUM>/m<NUM>), such as from about <NUM> lb/ft<NUM> (<NUM>/m<NUM>) to about <NUM> lb/ft<NUM> (<NUM>/m<NUM>), or from about <NUM> lb/ft<NUM> (<NUM>/m<NUM>) to about <NUM> lb/ft<NUM> (<NUM>/m<NUM>). The elastomeric material forming the buckling walls <NUM> may have a density of less than about <NUM> lb/ft<NUM> (<NUM>/m<NUM>), less than about <NUM> lb/ft<NUM> (<NUM>/m<NUM>), or even less than about <NUM> lb/ft<NUM> (<NUM>/m<NUM>).

The buckling walls <NUM> are formed of and comprise an elastomeric material. Elastomeric materials are described in, for example, <CIT>; <CIT>; and <CIT>. The elastomeric material includes an elastomeric polymer and a plasticizer. The elastomeric material may be a gelatinous elastomer (also referred to in the art as gel, elastomer gel, or elastomeric gel), a thermoplastic elastomer, a natural rubber, a synthetic elastomer, a blend of natural and synthetic elastomers, etc..

The elastomeric polymer may be an A-B-A triblock copolymer such as styrene ethylene propylene styrene (SEPS), styrene ethylene butylene styrene (SEBS), and styrene ethylene ethylene propylene styrene (SEEPS). For example, ABA triblock copolymers are currently commercially available from Kuraray America, Inc. , of Houston, TX, under the trade name SEPTON® <NUM>, and from Kraton Polymers, LLC, of Houston, TX, under the trade names KRATON® E1830, KRATON® G1650, and KRATON® G1651. In these examples, the "A" blocks are styrene. The "B" block may be rubber (e.g., butadiene, isoprene, etc.) or hydrogenated rubber (e.g., ethylene/propylene or ethylene/butylene or ethylene/ethylene/propylene) capable of being plasticized with mineral oil or other hydrocarbon fluids. The elastomeric material may include elastomeric polymers other than styrene-based copolymers, such as non-styrenic elastomeric polymers that are thermoplastic in nature or that can be solvated by plasticizers or that are multi-component thermoset or cross-linked elastomers.

The elastomeric material may include one or more plasticizers, such as hydrocarbon fluids. For example, elastomeric materials may include aromatic-free food-grade white paraffinic mineral oils, such as those sold by Sonnebom, Inc. , of Mahwah, NJ, under the trade names BIANDOL® and CARNATION®.

In some embodiments, die elastomeric material may have a plasticizer-to-polymer ratio from about <NUM>:<NUM> to about <NUM>:<NUM> by weight. For example, elastomeric materials may have plasticizer-to-polymer ratios from about <NUM>:<NUM> to about <NUM>:<NUM> by weight. or even from about <NUM>:<NUM> to about <NUM>:<NUM> by weight. In further embodiments, elastomeric materials may have plasticizer-to-polymer ratios of about <NUM>:<NUM> by weight.

The elastomeric material may have one or more fillers (e.g., lightweight microspheres). Fillers may affect thermal properties, density, processing, etc., of the elastomeric material. For example, hollow microspheres (e.g., hollow glass microspheres or hollow acrylic microspheres) may decrease the thermal conductivity of the elastomeric material by acting as an insulator because such hollow microspheres (e.g., hollow glass microspheres or hollow acrylic microspheres) may have lower thermal conductivity than the plasticizer or the polymer. As another example, metal particles (e.g., aluminum, copper, etc.) may increase the thermal conductivity of the resulting elastomeric material because such particles may have greater thermal conductivity than the plasticizer or polymer. Microspheres filled with wax or another phase-change material (i.e., a material formulated to undergo a phase change near a temperature at which a cushioning element may be used) may provide temperature stability at or near the phase-change temperature of the wax or other phase-change material within the microspheres (i.e., due to the heat of fusion of the phase change). The phase-change material may have a melting point from about <NUM> to about <NUM>.

The elastomeric material may also include antioxidants. Antioxidants may reduce the effects of thermal degradation during processing or may improve long-term stability. Antioxidants include, for example, pentaerythritol tetrakis(<NUM>-(<NUM>,<NUM>-di-tert-butyl-<NUM>-hydroxyphenyl) propionate), commercially available as IRGANOX® <NUM>, from BASF Corp. , of Iselin, New Jersey or as EVERNOX®-<NUM>, from Everspring Corp. , USA, of Los Angeles, California octadecyl-<NUM>-(<NUM>,<NUM>-di-tert-butyl-<NUM> -hydroxyphenyl)propionate, commercially available as IRGANOX® <NUM>, from BASF Corp. or as EVERNOX® <NUM>, from Everspring Chemical; and tris(<NUM>,<NUM>-di-tert-butylphenyl)phosphite, commercially available as IRGAFOS® <NUM>, from BASF Corp. or as EVERFOS® <NUM>, from Everspring Corp. One or more antioxidants may be combined in a single formulation of elastomeric material. The use of antioxidants in mixtures of plasticizers and polymers is described in columns <NUM> and <NUM> of <CIT>. The elastomeric material may include up to about <NUM> wt% antioxidants. For instance, the elastomeric material may include from about <NUM> wt% to about <NUM> wt% antioxidants.

In some embodiments, the elastomeric material may include a resin. The resin may be selected to modify the elastomeric material to slow a rebound of the elastomeric cushioning element <NUM> after deformation. The resin, if present, may include a hydrogenated pure monomer hydrocarbon resin, such as those commercially available from Eastman Chemical Company, of Kingsport, TN, under the trade name REGALREZ®. The resin, if present, may function as a tackifier, increasing the stickiness of a surface of the elastomeric material.

In some embodiments, the elastomeric material may include a pigment or a combination of pigments. Pigments may be aesthetic and/or functional. That is, pigments may provide an elastomeric cushioning element <NUM> with an appearance appealing to consumers. In addition, an elastomeric cushioning element <NUM> having a dark color may absorb radiation differently than an elastomeric cushioning element <NUM> having a light color.

The elastomeric material may include any type of gelatinous elastomer. For example, the elastomeric material may include a melt-blend of one part by weight of a sforene-ethylene-ethylene-propylene-styrene (SEEPS) elastomeric triblock copolymer (e.g., SEPTON® <NUM>) with four parts by weight of a <NUM>-weight straight-cut white paraffinic mineral oil (e.g., CARNATION® white mineral oil) and, optionally, pigments, antioxidants, and/or other additives.

The elastomeric material may include a material that returns to its original shape after deformation, and that may be elastically stretched. The elastomeric material may be rubbery in feel, but may deform to the shape of an object applying a deforming pressure better than conventional rubber materials, and may have a durometer hardness lower than conventional rubber materials. For example, the elastomeric material may have a hardness on the Shore A scale of less than about <NUM>, from about <NUM> to about <NUM>, or less than about <NUM>.

The elastomeric material may be generally nonsticky, such that the elastomeric cushioning element <NUM> may return to its original shape after a load is removed. That is, the elastomeric material may be sufficiently nonsticky so that buckling walls <NUM> do not stick to one another or do not remain stuck to one another after a deforming force is removed. In some embodiments, the buckling walls <NUM> may include a coating to make the surfaces of the elastomeric material nonsticky. Thus, any contact between adjacent buckling walls <NUM> may cease immediately or soon after the force is removed. The elastomeric material may be formulated to have any selected stickiness or tackiness, such as to control the rate of response to removal of a load.

Application of a force on the buckling walls <NUM> (e.g., weight of the cushioned object) causes a compression force on the buckling walls <NUM>. When the applied force to a particular buckling wall <NUM> exceeds a certain threshold value, that buckling wall <NUM> buckles, reducing die amount of force carried by that particular buckling wall <NUM> in comparison to the load it would have carried had it been constrained against buckling (e.g., resulting in a reduced slope of an associated stress-strain curve or load-deflection curve after buckling). The force on nearby buckling walls <NUM> may increase or change direction due to lateral transfer of the load through the buckling walls <NUM>.

The buckling of the buckling walls <NUM> may relieve pressure in the location of the buckling by decreasing the amount of the load carried by the buckled buckling walls <NUM> in comparison to die load they would have carried had they been constrained against buckling. Thus, a load may be transferred to other portions of the elastomeric cushioning element <NUM>. Transfer of all or a portion of the load to other portions of the elastomeric cushioning element <NUM> may reduce peak pressure, which may increase comfort for humans or animals, and may protect cushioned objects from damage. Such a load transfer may be particularly beneficial when an irregularly shaped object is placed against the buckling walls <NUM>.

<FIG> is a simplified drawing showing the mattress <NUM>, a portion of which is shown in <FIG>. The fabric <NUM> may partially or entirely surround the elastomeric cushioning element <NUM> and the foam base <NUM>. For example, the fabric <NUM> may be a single unitary stretchable material that covers five sides (e.g., top plus each of four lateral sides) or all six sides of the elastomeric cushioning element <NUM> and the foam base <NUM>. In some embodiments, there may be no sewn seam between the portion of the fabric <NUM> covering the top of the elastomeric cushioning element <NUM> and the portions of the fabric <NUM> covering the sides of the elastomeric cushioning element <NUM> and the foam base <NUM>. The fabric <NUM> may be sewn together in seams <NUM> only at the lateral corners of the mattress <NUM>. Limiting the length of the seams <NUM> may allow the fabric <NUM> to retain its stretchability. The fabric <NUM> may be secured to a bottom material <NUM> covering the bottom of the foam base <NUM> by a zipper <NUM>. The bottom material <NUM> may be a stretchable or non-stretchable material. In some embodiments, the bottom material <NUM> may be a portion of the fabric <NUM><NUM> continuous with a portion over one of the lateral sides of the mattress <NUM>. In such embodiments, the zipper <NUM> may connect the remaining three portions of the fabric <NUM> over the lateral sides of the mattress <NUM> to the bottom material <NUM>.

The mattress <NUM> may provide a combination of improved shock absorption and lower, more uniform pressure supporting cushioned objects in comparison with conventional mattresses. This combination may be beneficial in a variety of applications, such as in the protection of fragile devices (e.g., in shipping) or in human comfort (e.g., seat cushions, shoe inserts, etc.). Reduction of peak pressure may help humans or animals to avoid decubitus ulcers (also known as bed sores or pressure sores).

When a person or animal is resting on the mattress <NUM>, the fabric <NUM> may compress instead of or in addition to the compression of the elastomeric cushioning element <NUM> or the foam base <NUM>, such that the person is less aware of the presence of the buckling walls <NUM> of the elastomeric cushioning element <NUM>. That is, the person may not feel any particular buckling wall <NUM> or when the buckling walls <NUM> buckle. Alternatively, the buckling walls <NUM> or their buckling action may be felt by a user, but the feeling may be muted or diminished by the fabric <NUM>. Thus, the fabric <NUM> may make a mattress <NUM> including an elastomeric cushioning element <NUM> with buckling walls <NUM> more comfortable to a user than the elastomeric cushioning element <NUM> would be without the fabric <NUM> (e. g, with a conventional cover).

Furthermore, the construction of the fabric <NUM> as a single unitary sheet (i.e., as a single layer of material) may reduce production costs and retain stretchiness in comparison with a quilted material.

Claim 1:
A mattress or mattress topper (<NUM>), comprising:
a cushioning element (<NUM>) comprising an elastomeric material forming a plurality of intersecting buckling walls (<NUM>) defining a plurality of hollow columns (<NUM>), wherein the elastomeric material comprises an elastomeric polymer and a plasticizer; and
a knitted fabric (<NUM>) disposed over the cushioning element (<NUM>) and configured to move independently of the buckling walls (<NUM>) of the cushioning element (<NUM>), the knitted fabric (<NUM>) comprising:
a first layer (<NUM>) of stretchable material;
a second layer (<NUM>) of stretchable material; and
a layer of stretchable fill material (<NUM>) between the first layer (<NUM>) of stretchable material and the second layer (<NUM>) of stretchable material;
wherein the first layer (<NUM>) of stretchable material is knitted together with the second layer (<NUM>) of stretchable material as a unitary sheet of fabric including the layer of stretchable fill material (<NUM>);
wherein the knitted fabric (<NUM>) consists essentially of materials exhibiting stretchiness in at least two directions perpendicular to one another;
wherein the fabric (<NUM>) exhibits stretchiness in at least two directions perpendicular to one another.