CN111278330A

CN111278330A - Three-dimensional polylactide fiber matrix layers for bedding articles

Info

Publication number: CN111278330A
Application number: CN201880053296.XA
Authority: CN
Inventors: 凯文·奇拉卡尔; 麦肯齐·普雷斯特拉; 谢里·麦圭尔
Original assignee: Shuda Simmons Bedding Co Ltd
Current assignee: Shuda Simmons Bedding Co Ltd; Serta Simmons Bedding LLC
Priority date: 2017-08-17
Filing date: 2018-08-17
Publication date: 2020-06-12
Also published as: WO2019036557A1; JP7170044B2; JP2020531221A; CA3073201A1; DE112018004180T5; US20190053630A1

Abstract

A three-dimensional polymeric fiber matrix layer (10) for use in bedding articles such as mattresses is disclosed. The three-dimensional polymer fiber matrix layer (10) generally includes a plurality of randomly oriented Polylactide (PLA) fibers (12) bonded at tie points (16) between adjacent PLA fibers (12) and having a per unit area free volume.

Description

Three-dimensional polylactide fiber matrix layers for bedding articles

Technical Field

The present disclosure relates generally to bedding articles and methods of manufacture, and more particularly to bedding articles comprising a three-dimensional Polylactide (PLA) fiber matrix layer.

Background

One continuing problem associated with full foam mattress assemblies as well as hybrid foam mattresses (e.g., foam mattresses that include spring coils in addition to one or more foam layers, bladders that include fluids, and various combinations thereof) is user comfort. To address user comfort, mattresses are typically manufactured with multiple layers having different properties, such as density and firmness, to meet the needs of the intended user. One particular area of concern for user comfort is the level of heat buildup experienced by the user over a period of time. In addition, some mattresses may retain a high level of moisture, further causing discomfort to the user and potentially poor hygiene.

Unfortunately, the high density foams used in current mattress assemblies, particularly those employing traditional memory foam layers that typically have a fine cell structure and low air flow, often prevent proper ventilation. As a result, the foam material may exhibit a level of heat that is uncomfortable to the user after a period of time.

Disclosure of Invention

Disclosed herein are bedding articles comprising a three-dimensional Polylactide (PLA) polymer fiber matrix.

In one or more embodiments, a three-dimensional polymer fiber matrix layer for use in mattress construction includes a plurality of randomly oriented Polylactide (PLA) fibers bonded at connection points between adjacent PLA fibers and having a per unit area free volume.

In one or more embodiments, the mattress includes at least one three-dimensional PLA fiber matrix layer comprising randomly oriented PLA fibers bonded at connection points between adjacent fibers and having a free volume per unit area of the layer.

The present disclosure may be understood more readily by reference to the following detailed description of the various features of the disclosure and the examples included therein.

Drawings

FIG. 1 schematically illustrates a partial cross-sectional view of a foam-fiber composite layer including a three-dimensional polymer fiber matrix layer;

FIG. 2 schematically illustrates an exemplary system for preconditioning a three-dimensional polymeric fiber matrix layer;

FIG. 3 schematically illustrates an exemplary system for preconditioning a three-dimensional polymeric fiber matrix layer;

FIG. 4 depicts a top cross-sectional view of a mattress including a three-dimensional polymer fiber matrix layer;

FIG. 5 also depicts a top cross-sectional view of a mattress including a three-dimensional polymer fiber matrix layer;

fig. 6 schematically illustrates an exemplary mattress including a preconditioned three-dimensional polymer fiber matrix layer.

Fig. 4 and 5 depict a top view (top) and a side view (bottom), respectively, of a mattress 200 according to one embodiment of the present invention. The mattress 200 includes a mattress core 202 and at least one three-dimensional PLA fiber matrix layer 204 disposed on the mattress core 202 to provide a sleeping surface. The

portions

206 and 208 of the three-dimensional PLA matrix layer 204 may be treated differently. For example, portion 208 of the three-dimensional PLA matrix layer 204 may be preconditioned, while portion 206 is not. This results in certain portions of the mattress that may be stronger or softer and may be customized to match the user's sleeping posture. In other embodiments, different portions of the three-dimensional PLA matrix layer 204 may be pre-conditioned to different degrees. For example, one portion of the three-dimensional PLA matrix layer 204 may be compressed (or stretched) by an amount to provide a particular degree of firmness, while another portion of the three-dimensional polymer matrix layer 204 may be compressed or stretched by a different amount to provide a different degree of firmness. Optionally, the three-dimensional PLA matrix layer 204 may be pre-treated in more than two portions, and each portion may be pre-treated to provide different degrees of firmness.

Fig. 6 schematically shows a mattress 300 comprising a lower substrate layer 302, a three-dimensional polymer fiber matrix layer 304 and at least one upper foam layer 306, wherein the three-dimensional PLA fiber matrix layer 304 is located in the middle of the substrate layer 302 and the upper foam layer 306.

Detailed Description

The present disclosure overcomes the problems noted in the prior art by providing a mattress having one or more three-dimensional layers of polylactide fiber matrix. Polylactide Polymers (PLA) that define a three-dimensional fibrous matrix are also known as polylactic acid. PLA is a biodegradable thermoplastic aliphatic polyester derived from renewable sources, as opposed to traditional plastics that are typically derived from non-renewable petroleum sources. Several different types of suitable polylactide polymers include racemic PLLA (poly-L-lactic acid), conventional PLLA (poly-L-lactic acid), PDLA (poly-D-lactic acid), PDLLA (poly-DL-lactic acid), PLGA (polylactic-co-glycolic acid), PCL (polycaprolactone), and combinations thereof.

And are not intended to limit the position of one or more three-dimensional PLA fiber matrix layers within the mattress. In one or more embodiments, the three-dimensional PLA fiber matrix layer may be disposed near the surface or bottom of the mattress. In one or more other embodiments, the three-dimensional PLA fiber matrix layer is used as a transition layer between a base foam layer and one or more foam layers (e.g., a polyurethane foam layer, a latex foam layer, a viscoelastic foam layer, etc.) in a full foam mattress structure, or as a transition layer between an inner core and one or more foam layers in a hybrid mattress structure, which may further include a bladder, coil springs, etc. as a base layer.

The three-dimensional PLA fiber matrix layer can generally be formed by an extrusion process that results in a three-dimensional random fiber orientation, with the varying points of contact between the fibers acting as bond points to provide rigidity to the three-dimensional layer.

The three-dimensional PLA fiber matrix layer itself is subject to fatigue in the shear direction, as may occur when a user rolls over from side to side on a mattress comprising the three-dimensional polymer layer. As a result, the compaction of the three-dimensional polymeric fiber layer may occur as a function of use, which manifests itself as a change in firmness and a loss in height over time. To minimize the variation of the properties of the three-dimensional PLA fiber matrix layer with use, the three-dimensional polymer matrix layer may be subjected to a preconditioning process that disrupts the weaker bonds and/or structurally weaker fibers within the three-dimensional polymer fiber matrix layer.

Turning now to fig. 1, a three-dimensional PLA fiber matrix layer, generally designated by the reference numeral 10, is depicted. The three-dimensional PLA fiber matrix layer 10 includes randomly oriented PLA fibers 12, the randomly oriented PLA fibers 12 defining a significant number of voids 14, i.e., a relatively large amount of free space per unit area, wherein the free space is defined as the area not occupied by PLA fibers and is also referred to herein as voids. The three-dimensional PLA fiber matrix layer 10 includes a plurality of bond points 16 at the intersections between randomly oriented PLA fibers.

Generally, the three-dimensional PLA matrix layer 10 is formed by first extruding PLA to form a plurality of fibers. Dry granules, pellets, chips, etc. of PLA (having a moisture content of less than 250ppm) are fed into an extrusion device (i.e., an extruder) at elevated temperatures and pressures above the melting temperature of PLA (i.e., about 150 ℃ to about 170 ℃). The PLA in molten form is then extruded through a die, which is typically a plate comprising a number of spaced apart holes of defined diameter, where the position, density and diameter of the holes may be the same or different across the plate. When different, the three-dimensional PLA fibre layers can be made to have different density zones, for example the cross-sectional area can have different amounts of free volume per unit area. For example, the three-dimensional PLA fiber matrix layer may comprise a frame-like structure, wherein the outer peripheral portion has a higher density than the inner portion; or wherein the three-dimensional PLA fiber matrix layer may have a checkerboard pattern, wherein each square in the checkerboard has a different density than adjacent squares; or wherein the three-dimensional PLA fiber matrix layer may have different density portions corresponding to different expected weight loads of its user. The various configurations of the three-dimensional PLA fiber matrix layer are not intended to be limiting and may be tailored for any desired application. In this way, the solidity, i.e., indentation force deflection, and/or density of the three-dimensional PLA fiber matrix layer may be uniform or vary depending on the die configuration and conveyor speed.

The PLA feedstock is extruded into a cooling bath that causes the PLA fibers to entangle and bond by entanglement. Simultaneously, the continuously extruded cooled polymer matrix is drawn onto a conveyor. The transfer rate and cooling bath temperature can be independently varied to further vary the thickness and density of the three-dimensional polymeric fiber layer. Generally, the thickness of the three-dimensional PLA fiber matrix layer may itself be extruded into a full-width mattress material having a thickness in the range of about 1 to about 6 inches and may be produced in a set-top (topper) size or in roll form. However, thinner or thicker thicknesses and wider widths may also be used if desired. The three-dimensional PLA fiber matrix layer may have a thickness in the range of 0.5 to 5.9 inches.

Suitable extruders include, but are not limited to, continuous process high shear mixers such as: industrial melt plasticating extruders are available from a variety of manufacturers including, for example, Cincinnati-Millicron, Krupp Werner&Pfleiderer, Ramsey, N.J.07446, American Leistritz Extruder; somerville, n.j.08876; berstorff corporation, Charlotte, n.c.; and Davis-Standard div.Crompton&Knowles, Inc., Paweatuck, Conn.06379. Kneaders are available from Buss America; bloomington, il.; available from Draiswerke G.m.b.H., Mamnheim-Waldhof Germany or as Gelimat^TMThe high shear mixer of (1); and a Farrel continuous mixer available from Farrel corporation, Ansonia, Conn. Screw assemblies for mixing, heating, compressing and kneading operations are shown and described in Rauwendaal, Polymer extrusion, Hanser Publishers, New York (1986) pp.8 and 458-; meijer et al, "The Modeling of continuousmixers part 1: the Coroating Twin-Screen Extruder ", Polymer Engineering and science, Vol.28, No.5, pp.282-284 (3 months 1988); and Gibbons et al, "Extrusion", modern plastics Encyclopedia (1986-1987). The knowledge necessary to select extruder barrel elements and assemble the extruder screws is readily available from a variety of extruder suppliers and is well known to those of ordinary skill in the art of melt polymer mastication.

PLA fibers can be solid or hollow and have a cross-section that is circular or triangular or other cross-sectional geometries such as trilobe, channeled, etc. Another type of PLA fibers have an entangled spring-like structure. During manufacture, the PLA fiber structure is heated by extrusion to interconnect the fibers to one another to provide a more elastic structure. The fibers may be randomly oriented or directionally oriented, depending on the desired characteristics. Such a method is discussed in U.S. patent No. 8,813,286, entitled adjustable box spring mattress and method of making the same, which is incorporated by reference herein in its entirety.

The PLA fibers and their characteristics are selected to provide the desired tuning characteristics. One measure of the "feel" of the pad is the indentation force deflection, or IFD. Indentation force deflection is a metric used in the flexible foam manufacturing industry to evaluate the "firmness" of foam samples such as memory foam. For IFD testing, a circular flat indenter with a surface area of 323 square centimeters (50 square inches-diameter 8') was pressed against a foam sample, typically 100mm thick and 500mm by 500mm in area (ASTM standard D3574). The foam sample is first placed on a platform perforated to allow air to pass through. The pores were then opened by compressing twice to 75% "strain" and then allowed to recover for six minutes. The force was measured 60 seconds after 25% indentation was achieved with the indenter. Lower scores correspond to lower firmness; higher scores correspond to greater firmness. IFDs tested and configured in this manner for the three-dimensional PLA fiber matrix layer of a mattress have an IFD in the range of 5 to 25 lbf. The density of the three-dimensional PLA fiber matrix layer is in the range of 1.5 to 6lb/ft 3. After preconditioning, the three-dimensional PLA fiber matrix layer may have a density of 1.6 to 7lb/ft3 and an IFD of 4 to 24.9 lbf, if applicable.

As described above, in some embodiments, the three-dimensional PLA fiber matrix layer may be pre-conditioned. Fig. 2 depicts one embodiment of a system 50 capable of preconditioning a three-dimensional PLA fiber matrix layer 52 to provide more consistent and uniform firmness or stiffness across a surface 54 of the three-dimensional polymer fiber matrix layer 52 and for its useful life as a layer in a mattress. In particular, fig. 2 shows a mattress made with a three-dimensional PLA fiber matrix layer 52 mounted on top of a mattress core 54. The mattress core 54 is located on a table 60 above a moving platen 62. Platen 62 can be moved back and forth from the foot of the mattress to the head of the mattress as indicated by arrow 65 and, at the same time, robotic arm 64 is moved up and down as indicated by arrow 66. The robotic arm 64 is capable of cyclically processing the three-dimensional PLA fiber matrix layer 52 to apply mechanical force. The amount of mechanical force applied is selected to adjust the mechanical properties, such as IFD, of the three-dimensional PLA fiber matrix layer 52. The platen 62 carried on the robotic arm 64 can be moved across the entire surface of the mattress to machine the mattress substantially the entire length and width of the mattress. This provides more consistent firmness throughout the length and width of the mattress. In other embodiments, the three-dimensional PLA fiber matrix layer 52 may be first processed separately without the mattress core 54 and then disposed on the mattress core to provide a conditioned mattress assembly.

In one or more embodiments, deck 64 may be substantially similar in size to the sleeping area of the mattress and/or three-dimensional PLA fiber matrix layer 52. In such embodiments, the system 50 may be used to precondition a substantial portion of the mattress. Further, in such embodiments, the system 50 may be used to simultaneously precondition the head, body, and foot portions of the mattress surface. In still other embodiments, the system 50 may be configured as desired according to the nature of the preconditioning. For example, the deck 62 may be sized and shaped to selectively precondition a middle portion or an edge portion or both of the mattress and/or the three-dimensional PLA fiber matrix layer 52. In another embodiment, the system 50 may be configured with a plurality of platens 63 for preconditioning different portions of the mattress by applying similar or different loads. In certain embodiments, the platen 62 may be movable along the length or width of the mattress and equipped with cylindrical rollers so that the platen 62 may be rolled along the mattress surface to gradually compress the mattress and/or the three-dimensional PLA fiber matrix layer 52. Generally, in other embodiments and practices, the apparatus shown in fig. 2 can process only selected portions and areas of the three-dimensional PLA fiber matrix layer 52. In certain embodiments, the mattress can be posed (posturized) such that the mattress can be configured into zones having a plurality of different firmness. In such embodiments, the mattress can be positioned in selected zones having different firmness than other zones to promote natural alignment of the S-curve of your spine by adding additional support under the lower back and knees or to provide zones of different firmness for partners who sleep on the same mattress but require different firmness. It will be apparent to those skilled in the art that the area processed on the three-dimensional PLA fiber matrix layer 52 will depend on the application and may vary as desired. In certain embodiments, additional three-dimensional PLA fiber matrix layers (not shown) may be further disposed on the mattress to provide multiple layers. In one or more embodiments, each layer of the mattress can be formed from a three-dimensional PLA fiber matrix layer. Optionally, one or more of these additional three-dimensional PLA fiber matrix layers 52 may also be pre-conditioned by stress, compression, and/or tension as described herein to provide a mattress with multiple layers of pre-conditioned foam. Furthermore, it should be apparent that the mattress may include additional layers of foam, coil springs, and the like.

Fig. 3 depicts an alternative system 100 for processing a three-dimensional PLA fiber matrix layer 52. In the depicted embodiment, a pair of

counter-rotating rollers

102, 104 exert a force across the entire length and width of the three-dimensional polymer fiber matrix layer 52. The rolls may optionally be placed in an extrusion line, a cutting line, a mattress assembly line, or a transport assembly line so that the newly manufactured three-dimensional PLA fiber matrix layer 52 is processed as it is prepared in the factory. These and other suitable systems for preconditioning a three-dimensional PLA fiber matrix layer of the present disclosure are further disclosed in U.S. patent No. 7,690,096, which is incorporated herein by reference in its entirety.

Fig. 4 depicts a top view (top) and a side view (bottom) of a mattress 200 according to one embodiment of the present invention. The mattress 200 includes a mattress core 202 and at least one three-dimensional PLA fiber matrix layer 204 disposed on the mattress core 202 to provide a sleeping surface. The

portions

206 and 208 of the three-dimensional PLA matrix layer 204 may be treated differently. For example, portion 208 of the three-dimensional PLA matrix layer 204 may be preconditioned, while portion 206 is not. This results in certain portions of the mattress that may be stronger or softer and may be customized to match the user's sleeping posture. In other embodiments, different portions of the three-dimensional PLA matrix layer 204 may be pre-conditioned to different degrees. For example, one portion of the three-dimensional PLA matrix layer 204 may be compressed (or stretched) by an amount to provide a particular degree of firmness, while another portion of the three-dimensional polymer matrix layer 204 may be compressed or stretched by a different amount to provide a different degree of firmness. Optionally, the three-dimensional PLA matrix layer 204 may be pre-treated in more than two portions, and each portion may be pre-treated to provide different firmness.

Fig. 5 schematically shows a mattress 300 comprising a lower substrate layer 302, a three-dimensional polymer fiber matrix layer 304 and at least one upper foam layer 306, wherein the three-dimensional PLA fiber matrix layer 304 is located intermediate the substrate layer 302 and the upper foam layer 306.

Generally, the thickness of the lower substrate layer 302 is in the range of 4 inches to 10 inches, in other embodiments in the range of about 6 inches to 8 inches, and in still other embodiments in the range of about 6 inches to 6.5 inches. The lower substrate layer may be formed from an open or closed cell foam, including but not limited to viscoelastic foam, non-viscoelastic foam, latex foam, polyurethane foam, and the like.

The lower substrate layer 302 may have a density of 1 pound per cubic foot (lb/ft3) to 6lb/ft 3. In other embodiments, the density is from 1lb/ft3 to 5lb/ft3 and in still other embodiments from 1.5lb/ft3 to 4lb/ft 3. For example, the density may be about 1.5lb/ft 3. Indentation Force Deflection (IFD) is in the range of 20 to 40 pound-force, with hardness measured according to ASTM D-3574.

Alternatively, the lower base layer 302 may be a coil spring core disposed within a cavity defined by a bucket assembly, wherein the bucket assembly includes a planar base layer and side rails (siderails) disposed about a perimeter of the planar base layer.

The at least one upper foam layer 306 defines a cover panel covering the three-dimensional PLA matrix fiber layer 304. Depending on the intended application, the cover panel may be formed from one or more layers of viscoelastic foam and/or non-viscoelastic foam. The foam itself may be any open or closed cell foam material, including but not limited to latex foam, natural latex foam, polyurethane foam, combinations thereof, and the like. The cover panel has flat top and bottom surfaces. The thickness of the cover panel is typically in the range of about 0.5 to 2 inches in some embodiments, and less than 1 "in other embodiments to provide the benefits of motion separation and increased air flow from the underlying foam layer 104. The density of the at least one upper foam layer 306 is in the range of 1 to 5lb/ft3 in some embodiments, and in the range of 2 to 4lb/ft3 in other embodiments. Hardness is in the range of about 10 to 20 lbf in some embodiments, and less than 15 lbf in other embodiments. In one embodiment, the cover panel has a thickness of 0.5 ", a density of 3.4lb/ft3 and a hardness of 14 lbf.

In one or more embodiments, each of the various pluralities of stacked mattress layers 302, 304, and 306 can be formed from a three-dimensional PLA fiber matrix.

The various multiple stacked mattress layers 302, 304, and 306 may be adjacent to each other using an adhesive, or may be thermally bonded to each other, or mechanically fastened to each other, as desired for different applications.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

1. A mattress, comprising:

at least one three-dimensional PLA fiber matrix layer comprising randomly oriented PLA fibers bonded at junctions between adjacent fibers and having a per unit area free volume, wherein the at least one three-dimensional PLA fiber matrix layer is preconditioned such that a portion of the junctions are separated and a portion of the randomly oriented polymer fibers become fragmented to alter mechanical properties of the preconditioned three-dimensional PLA fiber matrix layer relative to the non-preconditioned three-dimensional polymer fiber matrix layer.

2. The mattress of claim 1 wherein said at least one three-dimensional PLA fiber matrix layer is located intermediate at least one upper foam layer and a lower substrate layer.

3. The mattress of claim 2 wherein said at least one upper foam layer comprises viscoelastic foam.

4. The mattress of claim 2 wherein said lower base layer comprises polyurethane foam or latex foam.

5. The mattress of claim 2 wherein said lower base layer comprises an inner core of coil springs disposed within a foam bucket assembly.

6. The mattress of claim 2 wherein said lower substrate layer and said at least one upper foam layer are formed from said three-dimensional PLA fiber matrix layer.

7. The mattress of claim 1, wherein the extruded three-dimensional PLA fiber matrix layer comprises a plurality of PLA fiber zones having different densities and/or indentation force offset values.

8. The mattress of claim 1, wherein said three-dimensional PLA fiber matrix layer has a height dimension of 1 to 6 inches.

9. The mattress of claim 1, wherein said three-dimensional PLA fiber matrix layer has an indentation force deflection in the range of 5 to 25 lbf.

10. The mattress of claim 1, wherein the PLA is selected from the group consisting of racemic PLLA (poly-L-lactic acid), regular PLLA (poly-L-lactic acid), PDLA (poly-D-lactic acid), PDLLA (poly-DL-lactic acid), PLGA (polylactic-co-glycolic acid), PCL (polycaprolactone), and combinations thereof.

11. The mattress of claim 1 wherein the change in mechanical property is a reduction in thickness of the preconditioned three-dimensional polymer fiber matrix layer relative to an unconditioned three-dimensional polymer fiber matrix layer.

12. The mattress of claim 1 wherein the change in mechanical property is a reduction in the deflection of the indentation force of the preconditioned three-dimensional polymer fiber matrix layer relative to the non-preconditioned three-dimensional polymer fiber matrix layer.