Mattress Construction Including Stitch-bonded Flame Barrier Having Stretch And Recovery Character

Abstract

A mattress construction having a resilient core incorporating deformable foam either alone or in combination with integrated springs with a complimentary flame barrier fabric disposed in overlying relation to the resilient core. The flame barrier fabric has a stitch-bonded construction with elastomeric yarns extending in stitched relation through a fleece substrate of substantially inelastic character incorporating a percentage of flame retardant fibers. In a relaxed condition, the fleece substrate is bunched between stitch lines formed by the elastomeric yarns. Upon the application of tension, the barrier fabric stretches by the extension of the elastomeric stitching yarns in combination with a flattening of the fleece substrate.

Description

TECHNICAL FIELD

[0001] This non-provisional application claims the benefit of, and priority from, U.S. provisional application 61/404,694 having a filing date of Oct. 7, 2010. The contents of such provisional application and all patent documents referenced herein are hereby incorporated by reference in their entirety as if fully set forth herein.

TECHNICAL FIELD

[0002] The present invention relates generally to residential and commercial mattresses and more particularly to mattresses incorporating one or more flame barrier panels disposed in overlying relation to a resilient foam core.

BACKGROUND OF THE INVENTION

[0003] It is known to provide mattresses with so called "flame barrier" materials positioned between a resilient mattress core and a decorative textile covering. In one approach, prior flame barrier materials have been formed from non-woven materials of fleece construction incorporating inherently flame retardant fiber constituents. While such constructions provide good flame blocking and insulation character, they have limited capacity to stretch and recover. This limitation may be particularly problematic with respect to mattresses which incorporate materials such as visco-elastic foam and the like which may be required to undergo substantial localized deformation.

[0004] In order to address the desire for stretch and recovery to match the underlying foam core materials, the industry has turned to the use of circular knitted products using filament and spun yarns. Such circular knit constructions may be formed from fibers having inherent flame resistance and/or may be treated with chemical compositions to provide enhanced flammability resistance. While circular knit structures tend to have good stretch and recovery character, their construction is such that when they are in a stretched condition interstices between the yarns open up. Under these conditions, the coverage of the underlying mattress core may be diminished. This reduced coverage thus reduces the insulating character of the barrier fabric in the tensioned state.

[0005] In light of the above deficiencies in the known art there is a continuing need for a mattress incorporating a flame barrier layer which has substantial stretch and recovery corresponding to an underlying core incorporating a deforming foam or other material either alone or in combination with integrated springs while providing continuous coverage over the full range of stretch.

SUMMARY OF THE INVENTION

[0006] The present invention provides advantages and alternatives over the prior art by providing a stretchable flame barrier material and more particularly, a mattress construction having a resilient core incorporating deformable foam either alone or in combination with integrated springs with a complimentary flame barrier fabric disposed in overlying relation to the resilient core. The flame barrier fabric has a stitch-bonded construction with elastomeric yarns extending in stitched relation through a fleece substrate of substantially inelastic character incorporating a percentage of flame retardant fibers. In a relaxed condition, the fleece substrate is bunched between stitch lines formed by the elastomeric yarns. Upon the application of tension, the barrier fabric stretches by the extension of the elastomeric stitching yarns in combination with a spreading (i.e. flattening) of the fleece substrate. This configuration provides continuous coverage over the full range of stretch. The barrier fabric may incorporate a substantially inelastic selvage to aid in processing and formation without curling.

[0007] Other exemplary aspects of the invention will become apparent upon review of the following detailed description of preferred embodiments and practices.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings, which are incorporated in, and which constitute a part of this specification, illustrate exemplary constructions and procedures in accordance with the present invention and, together with the general description of the invention given above and the detailed description set forth below, serve to explain the principles of the invention wherein:

[0009] FIG. 1 is a partial cut-away view of an exemplary mattress construction;

[0010] FIG. 2 is a cross-sectional view of the exemplary mattress construction of FIG. 1;

[0011] FIG. 3 is a needle point diagram illustrating a stitch forming arrangement for an exemplary flame barrier fabric for use in overlying relation to a resilient core in a mattress;

[0012] FIG. 4 is a schematic view illustrating an exemplary stitch-bonding operation;

[0013] FIG. 5 is a schematic view illustrating the arrangement of yarns in the exemplary flame barrier fabric of FIG. 3 in relaxed condition; and

[0014] FIG. 6 is a schematic view illustrating the arrangement of yarns in the exemplary flame barrier fabric of FIG. 3 in stretched condition.

[0015] While the invention has been illustrated and generally described above and will hereinafter be described in connection with certain potentially preferred embodiments and practices, it is to be understood that in no event is the invention limited to such illustrated and described embodiments and practices. On the contrary, it is intended that the present invention shall extend to all alternatives and modifications as may embrace the general principles of this invention within the full and true spirit and scope thereof. Also, it is to be understood that the phraseology and terminology used herein are for purposes of description only and should not be regarded as limiting. The use herein of terms such as "including" and "comprising" and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0016] Reference will now be made to the drawings, wherein to the extent possible like reference numerals are utilized to designate corresponding components throughout the various views. In FIG. 1 there is illustrated a mattress and box spring set 10 including a mattress 12 and an underlying supporting box spring 14. As will be appreciated, the mattress 12 may be used with or without the box spring 14. In the exemplary construction, the mattress 12 generally includes a core 16 of foam alone or in combination with supporting springs 18 (FIG. 2). By way of example only, and not limitation, the foam may be a visco-elastic polyurethane foam or the like having a density of about 1-12 pounds per cubic foot and more preferably about 3 to 7 pounds per cubic foot although other resilient foams and densities may likewise be utilized. The foam core 16 may have a continuous stiffness throughout the thickness of the mattress 12 or may be layered with varying stiffness levels at different positions in the thickness dimension.

[0017] In the illustrated arrangement, the core 16 is at least partially covered with an overlay structure 20 (FIG. 2). As illustrated, the overlay structure 20 includes at least one layer of a flame barrier fabric 30 of stitch-bonded construction. A covering layer 32 of decorative fabric or the like may be disposed in overlying relation to the flame barrier fabric 30. As will be appreciated, while the flame barrier fabric 30 is illustrated as being in direct contact with both the core 16 and the covering layer 32, it is likewise contemplated that one or more intermediate layers may be interposed between the flame barrier fabric 30 and the core 16 and/or between the flame barrier fabric 30 and the covering layer 32.

[0018] If desired, the flame barrier fabric 30 may be adjoined to the covering layer 32. Such connection may be at intermediate discreet positions, or may be along a substantially continuous interface. By way of example only, such connection may be made by quilting, adhesive bonding or other techniques as may be known to those of skill in the art.

[0019] As noted previously, the flame barrier fabric 30 is of a stitch-bonded construction. In such a construction yarns are stitched in parallel rows through a substrate material to define a coordinated structure. The stitches are formed at needles disposed across the width of the stitch-bonding machine. The stitching yarns may be shifted between needles to yield a desired pattern of yarn segments extending between stitch positions. By way of example only, an exemplary stitch-bonding operation is illustrated and described in U.S. Pat. No. 6,655,392 to Wildeman et al. the contents of which are incorporated herein by reference.

[0020] By way of example only, and not limitation, one exemplary construction for the flame barrier fabric 30 is illustrated in FIG. 3. As shown in FIG. 3 the exemplary flame barrier fabric 30 uses elastomeric stitching yarns 38 to form a stretch zone 40 of substantial width so as to substantially cover at least one side of the mattress 12. According to one exemplary practice, the elastomeric stitching yarn 38 may be a 140 denier SPANDEX yarn wrapped with a 150 denier, air entangled textured polyester yarn of substantially non-stretchable character. However, it is contemplated that any number of other wrapped or unwrapped elastomeric yarns may be used. By way of example only, alternative elastomeric components such as LYCRA.RTM., HYTREL.RTM., or the like may be substituted for SPANDEX. Likewise, varying deniers may be used for any of the yarn components. It is also contemplated that the wrapping yarn may be a material such as high stretch polyester, cold drawn flat polyester or the like.

[0021] By way of example only, one method contemplated for formation of a flame barrier fabric 30 in accordance with the present invention involves a so called two-bar stitch-bonding procedure shown schematically in FIG. 4. In the illustrated exemplary practice, one or more plies of a fleece substrate material 50 of fibrous nonwoven construction is conveyed to a stitch-forming position in the direction indicated by the arrow. As will be appreciated, while FIG. 4 illustrates the use of a single ply of substrate material 50, it is also contemplated that multiple plies may be used if desired.

[0022] During the stitch-bonding process a plurality of needles 54 (shown in greatly exaggerated dimension) pierce the substrate material 50 and engage elastomeric stitching yarns 38 delivered into position by the yarn guides of the front bar such that the stitching yarns are captured within a hook portion of the needles 54 (only one shown). The substrate material 50 may be held down by finger elements 56 (only one shown) to promote stability. In this regard, while only a single finger element 56 is shown, in actual practice a multiplicity of such elements may be positioned in adjacent relation across the width of the stitching zone. As the needle 54 is reciprocated downwardly, a closing element such as a closing wire which moves relative to the needle 54 closes the hook portion to hold the stitching yarns therein. With the hook portion closed, the captured stitching yarn is pulled through the interior of an immediately preceding yarn loop disposed around the shank of the needle 54 at a position below the substrate material 50. As the captured stitching yarn is pulled through the interior of the preceding yarn loop, a stitch is formed which is knocked off of the needle 54. As the needle 34 is raised back through the substrate material 50, the hook portion is reopened and a new yarn loop moves out of the hook portion and is held around the shank of the needle 54 for acceptance of the yarn and formation of a subsequent stitch during the next down stroke. As will be appreciated, while only a single elastomeric stitching yarn 38 and needle 54 are shown, a large number of such yarns and needles are arranged for interaction across the width of the stitch-bonding apparatus. Thus, during the formation process, elastomeric stitching yarns 38 may be shifted back and forth laterally between defined needles to simultaneously form a multiplicity of zigzag stitch lines extending in the machine direction across the width of the stretch zone 40 as shown in FIG. 3.

[0023] According to one exemplary practice, the substrate material 50 is formed from a blend of short staple fibers. The substrate material 50 may be subjected to carding or other stability enhancing procedures prior to stitching if desired. Typically, the fibers will have a length of about 6 inches or less although other lengths may be used. In one exemplary practice, the substrate material is made up of about 30% to about 100% silica rayon fibers in which flame retardant properties are enhanced by embedding silica in the cellulosic fiber (also known as FR Rayon or FR Viscose) or other self charring fibers and optionally about 5% to about 65% polyester fibers and optionally about 5% to about 25% para-aramid or meta-aramid fibers wherein all percentages are by weight. One potentially desirable blend includes 60% silica rayon fibers, 30% polyester staple fibers and 10% para-aramid staple fibers. Another potentially desirable substrate material is 100% silica rayon. The substrate material 50 preferably has a mass per unit area of about 80 to about 200 grams per square meter although higher or lower levels may be used. A mass per unit area of about 140 grams per square meter may be particularly desirable for some applications.

[0024] According to one contemplated practice, the elastomeric stitching yarns 38 may be stitched on a stitch-bonding machine at a 14 gauge setting (i.e. 14 needles per inch). In one exemplary practice, the elastomeric stitching yarns being partially threaded in a 1 miss 2 (1 in 2 out) manner as illustrated. Thus, every third needle engages an elastomeric stitching yarn 38. Of course, the unused needles may be removed and other threading arrangements may be used if desired. As illustrated, in the exemplary embodiment using this stitch notation the elastomeric stitching yarns 38 are stitched as flat stitches in a zigzag pattern between needle lines according to a stitch notation of 1-0, 3-4 thereby providing a relatively long transverse diagonal float segment between stitch points. As will be appreciated, the stitching is done with the yarns 38 in a stretched state. A stretched diagonal float distance between stitch points of about 0.20 cm or greater may be desirable. A stretched diagonal float distance of about 0.25 cm to about 5 cm or greater, and more preferably, about 0.4 cm to about 2.5 cm may be desirable in some environments of use. In this regard, the presence of substantial extendable length float segments is believed to promote elasticity in the final product in both the machine and cross-machine direction. Of course, other stitch notations may be used if desired.

[0025] The final fabric finished weight will normally be in the range of about 2 to 20 ounces per square yard. A finished weight in the range of about 6 to 12 ounces per square yard and more preferably about 9 ounces per square yard may be particularly desirable in some environments of use. Of course, other fabric weights may be used if desired.

[0026] As illustrated, in the exemplary construction the barrier fabric 30 also includes a pair of lateral selvage zones 60 which are substantially inelastic in character. In practice, the selvage zones 60 may be formed by stitching inelastic yarns 62 delivered from the yarn guides of the back bar in a pattern which limits stretch. By way of example only, the inelastic yarns 62 may be polyester yarns such as a 150 denier, 34 filament polyester flat yarn stitched in a chain stitch at a notation of 1,0/0,1 or the like. As shown, the inelastic yarns may be partially threaded such that every needle in the selvage zones is not engaged. In one exemplary practice, the inelastic stitching yarns being partially threaded in a 1 miss 2 (1 in 2 out) manner as illustrated. Thus, within the selvage zones, every third needle engages an inelastic elastomeric stitching yarn 62. Of course, the unused needles may be removed if desired and other threading arrangements may be used if desired.

[0027] In practice, the selvage zones 60 may have a relatively narrow width of about 1 to about 5 inches. By way of example only, a selvage width of about 3 inches on each side may be desirable in some environments of use. However, other widths may be used if desired. As will be appreciated, the presence of the substantially stretch-free selvage zones 60 provides dimensional stability to the overall structure during finishing and processing.

[0028] As indicated previously, the flame barrier fabric 30 may stretch substantially through the stretch zone by extension of the elastomeric stitching yarns 38 in combination with a spreading (i.e. flattening) of the fleece substrate. This behavior is best understood through joint reference to FIGS. 5 and 6. As shown, in the relaxed state (FIG. 5) the stitching yarns contract from their as-stitched condition and the substrate material 50 is bunched between stitch points of the elastomeric stitching yarns 38 on one side of the flame barrier fabric 30. This bunching defines an undulating pattern of parallel raised rows of the fleece substrate 50 extending in the machine direction of the fabric between the stitch points.

[0029] As illustrated in FIG. 6, upon the application of a tensioning force in the cross machine direction, the elastomeric stitching yarns 38 stretch and the rows of substrate material 50 flatten out. In this stretched condition the substrate material 50 continues to provide continuous coverage. Thus, the stretch zone 40 may be extended significantly without opening voids in coverage. Upon application of localized tensioning force in the machine direction, stretch may take place as the stitch lines are pulled towards one another and the crossing float segments of the elastomeric stitching yarns 38 are urged towards alignment with the machine direction. Without being limited to a specific theory, it is believed that the longer float segments formed by causing the elastomeric yarn to skip two or more needles between stitch points may facilitate stretching in the machine direction by permitting material contract laterally as it is extended longitudinally.

[0030] Due to the elastomeric nature of the stitching yarns 38, when tensioning forces are relieved, the flame barrier fabric reverts back to its low energy state (FIG. 5). Accordingly, the flame barrier fabric 30 exhibits substantial stretch and recovery character so as to conform to dimensional changes in the foam core 16. By way of example only, and not limitation, the exemplary material within the stretch zone 40 of a flame barrier fabric 30 formed as described herein may be stretched up to at least 50% (i.e. to 150% of its initial dimension) and more preferably up to 75% (i.e. to 175% of its initial dimension) in each of the machine direction and the cross-machine direction and thereafter recover to within 5 percent of its initial unstrained dimensions upon removal of the deforming force. Such elastomeric stretch and recovery character facilitates localized deformation for the foam core 16. Moreover, the exemplary material within the stretch zone 40 of a flame barrier fabric 30 formed as described herein may be characterized by a relatively low modulus of elasticity which is preferably lower than the compressive modulus of the foam core 16. Thus, upon application of a compressive force to the surface of the mattress, 12, the foam core 16 will provide greater resistance to deformation than the flame barrier fabric. The foam core 16 thereby substantially controls the level of support provided to a user while the flame barrier fabric 30 follows the dimensional changes in the foam core 16.

[0031] By way of example only, and not limitation, in both the machine direction and the cross-machine direction, the stretch zone 40 is preferably characterized by 50 percent elongation at less than about 500 grams applied force per centimeter width and more preferably by 50 percent elongation at less than about 300 grams applied force per centimeter width. That is, a 1 cm width of the material forming the stretch zone 40 may require no more than 500 grams applied stretching force (and more preferably no more than 300 grams applied stretching force) in order to stretch to 150% of its initial length.

[0032] In practice, the stretch zone of the flame barrier fabric 30 provides an effective insulating flame barrier across the foam core 16 in all stages of deformation since the substrate material 50 provides continuous coverage. Moreover, the fiber blend in the substrate material is highly effective in curtailing any flame propagation despite the presence of perforations formed during the stitch-bonding formation procedure. Specifically, upon exposure to a flame, the silica rayon fibers (or other FR constituent) forms a flame-blocking char which provides a stable flame barrier.

[0033] It is to be understood that while the present invention has been illustrated and described in relation to certain potentially preferred embodiments, constructions and procedures, that such embodiments, constructions and procedures are illustrative only and that the present invention is in no event to be limited thereto. Rather, it is contemplated that modifications and variations embodying the principles of this invention will no doubt occur to those of skill in the art. It is therefore contemplated and intended that the present invention shall extend to all such modifications and variations as may incorporate the broad aspects of the invention within the full spirit and scope thereof.

Claims

1. A mattress construction comprising: a deformable foam core comprising a foam having a density in the range of about 1 to 12 pounds per cubic foot; and a flame blocking overlay structure disposed at least partially around the foam core, wherein the overlay structure comprises at least one layer of flame barrier fabric of stitch-bonded construction having a machine direction and a cross-machine direction, the flame barrier fabric including an inelastic nonwoven fibrous substrate material including at least 30% by weight flame retardant fiber with a plurality of elastomeric yarns stitched through the fibrous substrate material, the elastomeric yarns defining a plurality of zigzag stitch lines extending in the machine direction of the flame barrier fabric, wherein the stitch lines include diagonal float segments extending between stitch points, wherein in an unstretched state, the fibrous substrate material is bunched in an undulating pattern defining a plurality of raised profile rows extending in the machine direction across one side of the flame barrier fabric, and wherein upon application of a stretching force, the flame barrier fabric is stretchable by at least 50% in each of the machine direction and cross-machine direction followed by elastic recovery to within 5% of the unstretched state upon removal of the stretching force.

2. The mattress construction as recited in claim 1, wherein the foam is visco-elastic polyurethane foam.

3. The mattress construction as recited in claim 2, wherein the foam has a density in the range of 3 to 7 pounds per cubic foot.

4. The mattress construction as recited in claim 1, wherein the foam surrounds internal springs.

5. The mattress construction as recited in claim 1, wherein the elastomeric yarns are wrapped yarns comprising an elastomeric core wrapped with inelastic textured yarn.

6. The mattress construction as recited in claim 1, wherein the nonwoven fibrous substrate material has a mass per unit area of about 80 to about 200 grams per square meter.

7. The mattress construction as recited in claim 1, wherein the nonwoven fibrous substrate comprises 30% to 100% silica rayon fibers and optionally about 5% to 65% polyester fibers and optionally about 5% to 25% para-aramid or meta-aramid fibers.

8. The mattress construction as recited in claim 1, wherein the nonwoven fibrous substrate comprises substantially 100% silica rayon fibers.

9. The mattress construction as recited in claim 1, wherein the flame barrier fabric is stretchable by at least 75% in each of the machine direction and cross-machine direction followed by elastic recovery to within 5% of the unstretched state upon removal of the stretching force.

10. The mattress construction as recited in claim 1, wherein a stretch zone of the flame barrier fabric is characterized by a modulus of elasticity in both the machine direction and the cross-machine direction such that 50 percent elongation requires less than 500 grams applied force per centimeter width.

11. The mattress construction as recited in claim 1, wherein a stretch zone of the flame barrier fabric is characterized by a modulus of elasticity in both the machine direction and the cross-machine direction such that 50 percent elongation requires less than 300 grams applied force per centimeter width.

12. The mattress construction as recited in claim 1, wherein the overlay structure includes covering layer of decorative fabric disposed in overlying relation to the flame barrier fabric.

13. A mattress construction comprising: a deformable foam core comprising a visco-elastic polyurethane foam having a density in the range of about 3 to 7 pounds per cubic foot; and a flame blocking overlay structure disposed at least partially around the foam core, wherein the overlay structure comprises a decorative outer fabric overlying at least one layer of flame barrier fabric of stitch-bonded construction having a machine direction and a cross-machine direction, the flame barrier fabric including an inelastic nonwoven fibrous substrate material including at least 30% by weight of carded silica rayon fiber with a plurality of elastomeric yarns stitched through the fibrous substrate material, the elastomeric yarns defining a plurality of zigzag stitch lines extending in the machine direction of the flame barrier fabric, wherein the stitch lines include diagonal float segments extending between stitch points at spaced-apart parallel needle lines, wherein in an unstretched state, the fibrous substrate material is bunched in an undulating pattern defining a plurality of raised profile rows extending in the machine direction across one side of the flame barrier fabric, and wherein upon application of a stretching force, the flame barrier fabric is stretchable by at least 50% in each of the machine direction and cross-machine direction followed by elastic recovery to within 5% of the unstretched state upon removal of the stretching force.

14. The mattress construction as recited in claim 13, wherein the foam surrounds internal springs.

15. The mattress construction as recited in claim 13, wherein the elastomeric yarns are wrapped yarns comprising an elastomeric core wrapped with inelastic textured yarn.

16. The mattress construction as recited in claim 13, wherein the nonwoven fibrous substrate material has a mass per unit area of about 80 to about 200 grams per square meter.

17. The mattress construction as recited in claim 13, wherein the nonwoven fibrous substrate comprises 30% to 100% silica rayon fibers and optionally about 5% to 65% polyester fibers and optionally about 5% to 25% para-aramid or meta-aramid fibers.

18. The mattress construction as recited in claim 1, wherein the nonwoven fibrous substrate comprises substantially 100% silica rayon fibers.

19. The mattress construction as recited in claim 1, wherein a stretch zone of the flame barrier fabric is characterized by a modulus of elasticity in both the machine direction and the cross-machine direction such that 50 percent elongation requires less than 500 grams applied force per centimeter width.

20. A mattress construction comprising: a deformable foam core comprising foam having a density in the range of about 3 to 7 pounds per cubic foot; and a flame blocking overlay structure disposed at least partially around the foam core, wherein the overlay structure comprises a decorative outer fabric overlying at least one layer of flame barrier fabric of stitch-bonded construction having a machine direction and a cross-machine direction, the flame barrier fabric including an inelastic nonwoven fibrous substrate material including at least 30% by weight of flame retardant cellulosic fiber with a plurality of elastomeric yarns stitched through the fibrous substrate material, the elastomeric yarns defining a plurality of zigzag stitch lines extending in the machine direction of the flame barrier fabric, wherein the stitch lines include diagonal float segments extending between stitch points at spaced-apart parallel needle lines, wherein in an unstretched state, the fibrous substrate material is bunched in an undulating pattern defining a plurality of raised profile rows extending in the machine direction across one side of the flame barrier fabric, and wherein upon application of a stretching force, the flame barrier fabric is stretchable by at least 50% in each of the machine direction and cross-machine direction followed by elastic recovery to within 5% of the unstretched state upon removal of the stretching force, and wherein a stretch zone of the flame barrier fabric is characterized by a modulus of elasticity in both the machine direction and the cross-machine direction such that 50 percent elongation requires less than 300 grams applied force per centimeter width.