Patent Application
20240065448
The present disclosure generally relates to mattress assemblies including foam layers exhibiting a reduced heat index.
Mattress assemblies including foam layers such as those formed of polyurethane foam, latex foam, and the like, are generally known in the art. One of the ongoing problems associated with mattress assemblies including foam layers in close proximity to the sleeping surface is user comfort. To address user comfort, these types of mattress assemblies are often fabricated with multiple foam layers having varying properties such as density and hardness, among others, to suit the needs of the intended user. More recently, manufacturers have employed so called memory foam, also commonly referred to as viscoelastic foams, which are generally a combination of polyurethane and one or more additives that increase foam density and viscosity, thereby increasing its viscoelasticity. These foams are often open cell foam structures having both closed and open cells but, in some instances, may be reticulated foam structures. The term “reticulated” generally refers to a cellular foam structure in which the substantially all of the membrane windows are removed leaving a skeletal structure. In contrast, open cell structures include both open cell (interconnected cells) and closed cells.
When used in a mattress, the memory foam conforms to the shape of a user when the user exerts pressure onto the foam, thereby minimizing pressure points from the user's body. The memory foam then returns to its original shape when the user and associated pressure are removed. Unfortunately, the high density of foams used in current mattress assemblies, particularly those employing memory foam layers, generally prevents proper ventilation. As a result, the foam material can exhibit an uncomfortable level of heat to the user after a period of time. Additionally, these foams can retain a high level of moisture, further causing discomfort to the user and potentially leading to foul odors. To overcome this, mattress manufacturers utilize phase change materials and/or thermally conductive materials such as graphite, metals, or the like within and/or on the foams layers to help dissipate heat. The thermally conductive material can be a composite of a carrier layer with high conductivity materials bonded to and/or impregnated in the carrier. These thermally conductive layers tend to be very good at moving heat away from a user on sleeping surface but also tend to be non-permeable, which can cause a buildup of humidity near the surface of the thermally conductive foam layer. These conductive materials need to be near the surface of the bed to be effective at moving heat away from the sleeper. The buildup of humidity near the sleeper will cause an undesirable increase in heat index and degrade the end user's sleep experience.
To reduce the buildup of humidity, mattress manufacturers have attempted to increase ventilation at the surface through the use of an overlying perforated foam layer and/or added perforations to the thermally conductive film layer. While movement of moisture will be improved as a function of the perforations, the moisture movement is still insufficient to significantly improve the sleep experience. Moreover, when an end user lays on the mattress, compression of the foam layers proximate to the sleeping surface, which typically includes the thermally conductive layer, results and serves to limit the amount of air flow through the perforations from the foam layer including the thermal conductive materials.
Disclosed herein are mattress assemblies including a spacer layer underlying and in direct with a thermally conductive layer and processes for reducing heat index in a mattress assembly. In one embodiment, the mattress assembly includes an upper foam layer; a thermally conductive layer underlying and in directed contact with the upper foam layer; and a spacer layer underlying and in direct contact with the thermally conductive layer, wherein the spacer layer comprises a three-dimensional polymeric fibrous structure including substantially planar top and bottom surfaces and substantially vertically oriented fibers extending between the planar top and bottom surfaces.
In another embodiment, the mattress assembly includes a thermally conductive layer proximate to a sleeping surface, the thermally conducive foam layer comprising thermally conductive particles within a foam matrix; and a spacer layer underlying and in direct contact with the thermally conductive layer, wherein the spacer layer comprises a three-dimensional polymeric fibrous structure including substantially planar top and bottom surfaces and substantially vertically oriented fibers extending between the planar top and bottom surfaces.
A process for reducing heat index in a mattress assembly includes placing a spacer layer under and in direct contact with a thermally conductive layer within a mattress assembly, wherein the spacer layer comprises a three-dimensional polymeric structure of fibers including planar top and bottom surfaces and fibers vertically extending from and connecting the bottom to the top surfaces, and wherein the thermally conductive layer comprises a thermally conductive material having a thermal conductivity greater than 5 watts per meters-Kelvin.
The 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.
Referring now to the figures wherein the like elements are numbered alike:
Prior Art
It should be appreciated that for simplicity and clarity of illustration, elements shown in the drawings have not necessarily been drawn to scale. For example, the dimensions of some of the elements could be exaggerated relative to other elements for purpose of clarity.
Disclosed herein are mattress assemblies that provide improved airflow, moisture reduction, and a reduced heat index to effectively dissipate user heat and moisture during use. Applicants have found that the heat index in mattress assemblies including a thermally conductive layer sandwiched between foam layers proximate to the sleeping surface can be markedly reduced by utilizing a spacer layer under the thermally conductive layer so that heat and moisture can be exhausted away from the upper surface and through the spacer layer of the mattress assembly. In some embodiments, the layers above the spacer layer such as the thermally conductive layer can be perforated to further increase air flow. In other embodiments, one or more of the layers and/or surfaces thereof can also include a phase change material.
Detailed embodiments of the mattress assemblies according to aspects of the present invention will now be described herein. However, it is to be understood that the embodiments of the disclosure described herein are merely illustrative of the structures that can be embodied in various forms. In addition, each of the examples given in connection with the various embodiments of the invention is intended to be illustrative, and not restrictive. Further, the figures are not necessarily to scale, some features can be exaggerated to show details of particular components. Therefore, specific structural and functional details described herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the methods and structures of the present description. For the purposes of the description hereinafter, the terms “upper”, “lower”, “top”, “bottom”, “left,” and “right,” and derivatives thereof shall relate to the described structures, as they are oriented in the drawing figures. The same numbers in the various figures can refer to the same structural component or part thereof.
As used herein, the articles “a” and “an” preceding an element or component are intended to be nonrestrictive regarding the number of instances (i.e. occurrences) of the element or component. Therefore, “a” or “an” should be read to include one or at least one, and the singular word form of the element or component also includes the plural unless the number is obviously meant to be singular.
As used herein, the terms “invention” or “present invention” are non-limiting terms and not intended to refer to any single aspect of the particular invention but encompass all possible aspects as described in the specification and the claims.
The following definitions and abbreviations are to be used for the interpretation of the claims and the specification. As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” “contains” or “containing,” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, a mixture, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such composition, mixture, process, method, article, or apparatus.
As used herein, the term “about” modifying the quantity of an ingredient, component, or reactant of the invention employed refers to variation in the numerical quantity that can occur, for example, through typical measuring and liquid handling procedures used for making concentrates or solutions. Furthermore, variation can occur from inadvertent error in measuring procedures, differences in the manufacture, source, or purity of the ingredients employed to make the compositions or carry out the methods, and the like. In one aspect, the term “about” means within 10% of the reported numerical value. In another aspect, the term “about” means within 5% of the reported numerical value. Yet, in another aspect, the term “about” means within 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% of the reported numerical value.
It will also be understood that when an element, such as a layer, region, or substrate is referred to as being “on” or “over” another element, it can be directly on the other element or intervening elements can also be present. In contrast, when an element is referred to as being “directly on” or “directly over” another element, there are no intervening elements present, and the element is in contact with another element.
Various embodiments of the invention are described herein with reference to the related drawings. Alternative embodiments of the invention can be devised without departing from the scope of this invention. Various connections and positional relationships (e.g., over, below, adjacent, etc.) are set forth between elements in the following description and in the drawings. These connections and/or positional relationships, unless specified otherwise, can be direct or indirect, and the present invention is not intended to be limiting in this respect. Accordingly, a coupling of entities can refer to either a direct or an indirect coupling, and a positional relationship between entities can be a direct or indirect positional relationship. Moreover, the various tasks and process steps described herein can be incorporated into a more comprehensive procedure or process having additional steps or functionality not described in detail herein.
As used herein, the term “spacer layer,” also commonly referred to by those skilled in the art as “spacer fabric”, is an extruded three-dimensional polymeric matrix having multiple layers of varying materials in a sandwiched configuration. The spacer layer can be of a sufficient thickness and have suitable compressive properties (e.g., resilience and/or resistance) for providing some cushioning effect when used in conjunction with a mattress, mattress topper, or other cushioning element. The spacer layer generally includes multiple and randomly oriented fibers, i.e., monofilaments, extending from a top surface to a bottom surface. The spacer layer can have a free volume greater than 50% or more and can be formed of an elastomeric material that maintains its original shape subsequent to compression. Moreover, when compressed, the spacer layer generally maintains a percentage of free volume such that air flow through the layer is maintained via reduced localized buckling, which is unlike compression of foams that can undergo complete collapse of the pores and/or cells and/or tortuous pathways within the foam layer depending on the compressive load.
PRIOR ART
The upper foam layer 14 can be the uppermost layer and is often referred to as a cover layer. The upper foam layer 14 generally has a planar top surface adapted to substantially face the user resting on the mattress assembly and having a length and width dimensions sufficient to support a reclining body of the user. The lower surface can be a planar surface or a convoluted surface. The upper foam layer 14 is relatively thin so that the presence of the underlying thermally conductive layer can effectively wick heat from the sleeping surface during use by an end user thereon to provide the end user with reduced heat buildup as a consequence of the well-known insulative properties of foam.
The lower layer 16 can be a foam layer or an innerspring mattress core.
Other than optional perforations (i.e., through holes), the non-perforated portions of the thermally conductive layer 12 are generally not permeable due to the presence of the thermally conductive material within and/or on the non-perforated portion, Which can cause buildup of moisture during use by the end user near the surface of the thermally conductive layer. The buildup of moisture near the surface causes a subsequent increase in heat index, which degrades the end users' sleep experience. To overcome this, some manufacturers have provided perforations in the thermally conductive layer as is generally shown. However, Applicants have discovered that the subsequent compression of the foam layers proximate to the sleeping surface as shown in the mattress assembly depicted in PRIOR ART
In the present disclosure, Applicants have found that providing a spacer layer as will be described in greater detail herein directly under and in contact with the thermally conductive layer substantially reduces moisture buildup during use and provides a markedly lower heat index than the prior art mattress assemblies.
Turning now to
As noted above, the spacer layer 116 is an extruded three-dimensional polymeric fiber layer that includes a plurality of random polymeric fibers that can bond at intersections between fibers and generally extend between a top planar surface and a bottom planar surface of the spacer layer. The spacer layer 116 has a free volume that is generally greater than 50%. Relative to foams, the spacer layer 116 is not a foam and does not include defined cells or pores. Instead, the spacer layer 116 generally includes fibers, i.e., monofilaments, that randomly connect opposing fibers defining the outer planar (porous) surfaces of the spacer layer 116 to form the three-dimensional structure. Because of the lower elasticity caused by the increased stiffness of the monofilaments extending and/or intersecting between the two surfaces, the microclimate upon compression such as provided by an end user during use thereof is maintained unlike foams. Consequently, moisture does not buildup near the surface of the thermally conductive layer 112 upon compression but instead can advantageously flow further from the sleeping surface to a layer underlying the spacer layer 116, which has been found to markedly reduce the heat index.
Generally, the spacer layer 116 is formed by extruding the desired three dimensional polymeric fibers. Granules, pellets, chips, or the like of a desired polymer along can be fed into an extrusion apparatus, i.e., an extruder, at an elevated temperature and pressure, which is typically greater than the melting temperature of the polymer. The polymer, in melt form, is extruded through a die, which generally is a plate including numerous spaced apart apertures of a defined diameter, wherein the placement, density, and the diameter of the apertures can be the same or different throughout the plate. When different, the three-dimensional polymeric fiber matrix layer can be made to have different zones of density, e.g., sectional areas can have different amounts of free volume per unit area. For example, the three dimensional polymeric fiber matrix layer can include a frame-like structure, wherein the outer peripheral portion has a higher density than the inner portion; or wherein the three dimensional polymeric fiber layer has a checkerboard-like pattern, wherein each square in the Checkerboard has a different density than an adjacent square; or wherein the three-dimensional polymeric fiber layer has different density portions corresponding to different anticipated weight loads of a user thereof. The various structures of the extruded three-dimensional polymeric fiber are not intended to be limited and can be customized for any desired application. In this manner, the firmness, i.e., indention force deflection, and/or density of the extruded three-dimensional polymeric fiber matrix layer can be uniform or varied depending on the die configuration and conveyor speed.
The polymer is extruded into a cooling bath, which results in entanglement and bonding of polymeric fibers through entanglement. Concurrently, the continuously extruded, cooled polymeric matrix is pulled onto a conveyor. The rate of conveyance and cooling bath temperature can be individually varied to thither vary the thickness and density of the three-dimensional polymeric fiber matrix layer. Generally, the thickness of the extruded three-dimensional polymeric fiber matrix layer can be extruded as a full width mattress material.
In other embodiments, the spacer layer 116 is fabricated using additive manufacturing techniques.
The polymer in the spacer layer 116 may be formed from polyesters, polyethylene, polypropylene, nylon, elastomers, copolymers and its derivatives, including monofilament or bicomponent filaments having different melting points. In one example, the polymer is an engineered polyester material. An exemplary polymer fiber structure according to this disclosure is formed of core polyester fibers that are sheathed in a polyester elastomer binder.
The thermally conductive layer in the mattress assemblies according to the present disclosure can be formed of foam and includes a plurality of thermally conductive particles embedded therein and dispersed throughout the foam layer and/or a foil on a surface there of.
The thermally conductive particles and/or foil can be formed of metals, metal oxides, polymers, inorganic compounds and the like. By way of example, suitable thermally conductive materials may be made of carbon, graphene, graphite, platinum, aluminum, diamond, gold, silver, silicon, tin, copper, iron, nickel, chromium, vanadium, tungsten and the like or made from any of those materials combined with oxygen, halogens, carbon, or silicon, or any combination thereof; polymers such as stretched polyethylene nanofibers; and the like, and mixtures thereof. Particles can be in the form of fibers, powder, flakes, needles, and the like and are generally dispersed within the foam layer.
In most embodiments, the selected thermally conductive material has a thermal conductivity greater than 5 watts per meters-Kelvin (W/m*K). By way of example, aluminum has a thermal conductivity of about 235 W/m*K; stretched polyethylene fibers is estimated to be about 180 W/m*K, and graphene has a theoretical conductivity of about 5000 W/m*K. In contrast, foams utilized in mattresses by themselves are typically insulating having thermal conductivity values of about 0.06 W/(mK) or less.
Exemplary foams include polymeric elastomers including, but are not limited to, polyurethane foams, latex foams including natural, blended and synthetic latex foams: polystyrene foams, polyethylene foams, polypropylene foam, polyether-polyurethane foams, and the like. Likewise, the foam can be selected to be viscoelastic or non-viscoelastic foams. Some viscoelastic foam materials are also temperature sensitive, thereby enabling the foam layer to change hardness/firmness based in part upon the temperature of the supported part, e.g., person. Unless otherwise noted, any of these foams may be open celled or closed cell or a hybrid structure of open cell and closed cell. Likewise, the foams can be reticulated, partially reticulated or non-reticulated foams. The term “reticulation” generally refers to removal of cell membranes to create an open cell structure that is open to air and moisture flow. Still further, the foams may be gel-infused in some embodiments in addition to the incorporation of the thermally conductive fibers. These same materials can be used for any of the foam layers in the mattress assembles of the present disclosure that do not include the thermally conductive fibers incorporated therein, e.g., in the case of a foam base core layer, the layer may be composed of polyurethane foam, wherein the upper foam layer is a viscoelastic foam layer.
The various foams suitable for use in the thermally conductive polymeric foam layer or elsewhere may be produced according to methods known to persons ordinarily skilled in the art. For example, polyurethane foams are typically prepared by reacting a polyol with a polyisocyanate in the presence of a catalyst, a blowing agent, one or more foam stabilizers or surfactants and other foaming aids. The gas generated during polymerization causes foaming of the reaction mixture to form a cellular or foam structure. Latex foams are typically manufactured by the well-known Dunlap or Talalay processes. The thermally conductive fibers can be added during polymerization, prior to curing, prior to forming the voids, or the like. Manufacturing of the different foams are well within the skill of those in the art. It should be apparent to those skilled in the art of foam manufacturing that the distribution of the thermally conductive materials may be heterogeneous, homogenous, stratified, or the like. B way of example, a homogenous distribution would maintain a thermal gradient through the thickness of the layer providing a pathway for heat transfer for the surface closest to the sleeping surface to the interior, i.e., towards the base core layer. An example of a heterogeneous structure, e.g., stratified, may include heavier loading of the conductive filler or stabilizer at a surface of the polymer material. This implementation would provide improved thermal transfer across the surface of the polymer layer.
The thickness of the thermally conductive layer 112 is not intended to be limited and is generally less than 3 inches. In other embodiments, the thermally conductive layer 112 is less than 2 inches and in still other embodiments, the thickness is less than 1 inch. If a thermally conductive film or foil is used as the conductive layer 112 the thickness can be less than 0.125 inches. Optionally, the thermally conductive layer 112 can be perforated.
In one or more embodiments, the upper foam layer 114 can be formed of a viscoelastic polyurethane foam. The viscoelastic polyurethane foam can have an open cell structure and has planar top and bottom surfaces. The thickness of the upper layer is generally less than 3″ in some embodiments, less than 2″ in other embodiments, and less than 1 inch in still other embodiments. The density of the upper foam layer is less than 6 lb/ft3 in some embodiments, and less than 2.5 lb/ft3 in other embodiments. In one embodiment, the hardness is generally less than 15 pounds-force.
The different properties for each layer including foam may vary depending on the intended application. The different properties include, but are not limited to, density, hardness, thickness, support factor, flex fatigue, air flow, various combinations thereof, and the like. Density is a measurement of the mass per unit volume and is commonly expressed in pounds per cubic foot. By way of example, the density of the each of the foam layers can vary. In some embodiments, the density decreases from the lower most individual layer to the uppermost layer. In other embodiments, the density increases. In still other embodiments, one or more of the foam layers can have a convoluted surface. The convolution may be formed of one or more individual layers with the foam layer, wherein the density is varied from one layer to the next. The hardness properties of foam are also referred to as the indention load deflection (ILD) or indention force deflection (IFD) and are measured in accordance with ASTM D-3574, Like the density property, the hardness properties can be varied in a similar manner. Moreover, combinations of properties may be varied for each individual layer. The individual layers can also be of the same thickness or may have different thicknesses as may be desired to provide different tactile responses.
The hardness (i.e., indention load deflection, (ILD)) of any of the foam layers in the mattress assembly can range from 7 to 25 pounds force for viscoelastic foams and from 7 to 55 pounds force for iron-viscoelastic foams. ILD can be measured in accordance with ASTM D 3575. The density of the layers can generally range from about 1 to 2.5 pounds per cubic foot for non-viscoelastic foams and 1.5 to 7 pounds per cubic foot for viscoelastic foams.
In this example, average heat index as a function of time was measured for various mattress assemblies provided on a standard foundation. The various mattress assemblies included a perforated thermally conductive layer sandwiched between foam layers, and mattress assemblies including a perforated thermally conductive layer sandwiched between foam layers and a spacer layer underlying and in direct contact with the thermally conductive layer. In each of the mattress assemblies, the upper foam layer was a viscoelastic foam layer having a thickness of ½ inch to 1 inch, an ILD of 8, and a density of 2.3 pounds per cubic foot. The thermally conductive layer was the same in each mattress assembly and included a ventilated thermally conductive film having a thickness of 0.0625 inches. Particles of carbon in the form of graphite and graphene were uniformly dispersed throughout the layer and the layer further included 1-inch perforations unfirmly spaced throughout the layer at about a 1-inch spacing. The spacer layer was a 100% polyester fiber layer having a thickness of 5 millimeters commercially available from Eastex Products, Inc. under the tradename Breathable Airmesh. The spacer layer included two opposing fabric coverings having a diamond-like surface connected with filaments.
Average heat index was measured for the various mattress assemblies with and without the spacer layer using a FluxDAQ heat flux sensor and thermocouple measurement system commercially available from FluxTeq. The sensors were provided on surfaces of each test mattress to evaluate the microclimate that a sleeper might experience during use. A guarded hot plate including an 11.25 pound weight was placed on a sleeping surface for each mattress being tested and was heated to 98° F. The guarded hot plate was configured to leak a controlled amount of moisture as a function of time to simulate the lower back of an end user, which is considered the sweatiest part of the body. For each mattress, the arrangement was then covered with a 300-thread count cotton flat sheet and two fleece blankets. The measurement system recorded data from the temperature and humidity sensors for a period of 8 hours. The data is graphically presented in
As shown, mattress assemblies without the spacer layer were greater than 10 degrees Fahrenheit (° F.) hotter at the end of an 8-hour period than mattress assemblies including the spacer layer underlying and in directed contact with the thermally conductive layer. It is believed that the mattress assemblies including the perforated thermally conductive layer sandwiched between foam layers compressed under the end users' weight (load) and did not permit movement of humidity and heat, resulting in a marked increase in heat index to the end user in a fairly short period of time that extended throughout the test period of 8 hours. In contrast, mattress assemblies including the spacer layer more effectively prevented heat and humidity build up under load allowing the heat and humidity to freely flow within the spacer layer and into the underlying layers. Surprisingly, the perforations in the thermally conductive layer were less restricted with the underlying spacer layer being present in the mattress assembly.
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 examples 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.
