Mattresses Having a Matrix Core of Foam Elements

Abstract

A mattress is constructed of a core comprising a matrix of foam pieces that are bonded together. The core has a thickness in the range from about 1.5 inches to about 10 inches, and more particularly from about 3 inches to about 8 inches, a density of about 4 pounds to 8 pounds per cubic foot, and an IFD of about 28 to 65. The core has a top surface and a bottom surface. A base layer is coupled to the bottom surface of the core, and a cushion layer is coupled to the top surface.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Serial No. 61/554,413, filed Nov. 1, 2011, titled “Mattresses Having a Matrix Core of Foam Elements,” the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

This invention relates generally to the field of mattresses. In particular, the invention relates to mattress that utilize a core made up of a matrix of foam elements.

Spring mattresses have been in use for over 100 years. Existing spring mattresses use a variety of spring types to form their inner core. Perhaps the most common is the traditional wire spring assembly having a set of interconnected wire spring coils.

As manufacturing processes have improved, it is becoming more common to use other types of cores, including cores made of a single material, such as a core constructed from a solid piece of latex or polyurethane.

This invention relates to mattress using other types of cores. Such cores take advantage of reclaimed or repurposed materials that would otherwise be discarded (e.g., as being unusable cut sizes or foam densities after foam manufacturing runs).

BRIEF SUMMARY OF THE INVENTION

In one embodiment, the invention provides a mattress that is constructed of a core comprising a matrix of foam pieces that are bonded together. The core has a thickness in the range from about 1.5 inches to about 10 inches, and more particularly from about 3 inches to about 8 inches, a density of about 4 pounds to 8 pounds per cubic foot, and an Indentation Force Deflection (IFD) of about 28 to 65. For convenience of discussion, the core may have a top surface and a bottom surface. A base layer is coupled to the bottom surface of the core, and a cushion layer is coupled to the top surface. In this way, remnant foam pieces that may otherwise be discarded may be used to form a relatively dense mattress core. For example, the foam pieces may comprise polyurethane, urethane and the like.

In one aspect, the cushion layer comprises a visco-elastic material. In another aspect, a top layer is positioned above the cushion layer. A flame or fire retardant sock (referred to as an FR sock) may also be provided to enclose the completed mattress. Per regulations, this provides a covering for the mattress that meets an open flame standard. Alternatively, a flame retardant or resistant fiber layer may be provided below quilting if desired. Further, a cover, also known as a ticking, is typically employed to envelope the core, the base layer and the cushion layer. The cover may also be either quilted (to form a pillow top mattress), a plush quilted or non-quilted.

In a further embodiment, the invention provides an exemplary method for constructing a mattress. In one step of the process, a loaf is formed by combining a plurality of foam pieces and a bonding material into a generally rectangular mold and applying heat. In this way, the resulting loaf has a top, a bottom and four sides. To form a core, a rectangular section is cut from the loaf, and will typically have a thickness in the range from about 3 inches to about 8 inches. The resulting core may have a density in the range from about 4 pounds to about 8 pounds and an IFD in the range from about 28 to about 65. A base layer is attached to a bottom surface of the core, and a cushion layer is attached to a top surface of the core. Typically, a cover is placed about the mattress.

The mattresses described herein may be useful as mattresses for conventional beds, but they may also be useful for mattresses used with a sleeper sofa, camper beds, yacht beds, cruise-ships beds, play mats, gym mats, camping pads, nap pads, or any other potential use where a core with a padded surface may be desirable. The term “mattress” as used herein is intended to encompass these and other appropriate uses.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic cross sectional side view of one embodiment of a mattress according to the invention.

FIG. 2 is an exploded schematic top perspective view of the mattress of FIG. 1, showing various component layers, not necessarily to scale.

FIG. 3 illustrates a schematic cross sectional side view of another embodiment of a mattress according to the invention.

FIG. 4 illustrates a mattress according to one of the embodiments described herein, with a layer of ticking disposed over the foam core, base layer, and cushion layer.

FIG. 5 illustrates a cross-sectional view of another mattress according to one embodiment of the invention.

FIG. 6 illustrates the mattress of FIG. 5, having various component layers rolled back at one corner.

FIGS. 7-12 illustrate testing results for certain mattresses according to various embodiments of this invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention provide various mattress that utilize a core made up of a matrix of foam pieces or elements that are bonded together. The core is relatively dense, significantly more dense than traditional polyurethane cores. This increased density provides a stronger and more durable core while providing a more comfortable feel. Another significant advantage of using a matrix of foam pieces is that such foam pieces may be repurposed or otherwise reclaimed materials. Not only is this friendly to the environment, it also significantly reduces the cost of the mattress.

Hence, the core may be constructed to have a high density along with a durable construction to provide increased life. This matrix of foam pieces is also firm and is constructed of a variety of small urethane or other foam pieces (typically re-purposed foam pieces, for example new foam that cannot be cut into other pieces of the desired size or sections of foam that are not the desired density for other purposes, allowing the foam to be re-purposed in a new fashion) that are joined together using an adhesive, heat and steam that tend to increase the density. One particularly useful method for constructing cores using such a process is described hereinafter.

Further, the core may be constructed to be relatively dense, has an IFD in the range from about 28 to about 65 and is relatively inexpensive. Other types of materials that may be used include polystyrene materials, polyurethane, densified fibers and the like. The IFD, or Indentation Force Deflection, refers to the hardness or softness of the foam. For example, the higher the IFD, the firmer the foam. IFD is defined as the amount of force, in pounds, required to indent a fifty square inch, round indentor foot into a predefined foam specimen a certain percentage of the specimen's total thickness. IFD is specified as a number of pounds at a specific deflection percentage on a specific height foam sample, e.g., 25 pounds applied to 50 square inches at a 25% deflection on a four inch thick piece.

A wide variety of optional layers may be coupled to the top and/or bottom surface of the core. For example, another dense foam material may be coupled to the bottom of the core. A variety of layers may be placed on top of the core, including additional padding layers, ticking, foam, a quilted layer, or the like.

In some embodiments, one or more cushion layers may be placed above the core. These may be constructed of a material such as a polyurethane or latex foam, a visco-elastic or memory foam material, or the like. These additional padding layers may be used to provide the mattress with additional comfort and may be used alone or in various combinations. One or both sides of these cushion layers may be surface modified using various machining processes. Examples of surface modifications include convoluted, contoured, and the like. Other materials that may be used include fiber padding materials. Further, mattresses of the invention may include a layer of ticking that is a piece of fabric or quilting that envelopes the mattress as is known in the art. The ticking may comprise essentially any type of fabric or covering and may be sewn to form it around the core and other padding layers.

Referring now to FIGS. 1 and 2, one embodiment of a mattress 10 will be described. Mattress 10 includes a core 12 that is constructed of a plurality of foam pieces that are bonded together to form a matrix. Core 12 typically has a thickness in the range from about 3 inches to about 8 inches, but may range anywhere from 1.5 inches to about 10 inches. One specific embodiment has a core that is about 4.5 inches to about 7.5 inches. In a particular embodiment, the core thickness may range from about 3 inches to about 5 inches, and may specifically be about 4.5 inches. In an alternate embodiment, the core thickness may range from about 4 inches to about 6 inches, and may specifically be about 5.5 inches. In a further embodiment, the core thickness may range from about 6 inches to about 8 inches, and may specifically be about 7.5 inches. The core should be thick enough to provide appropriate support for sleeping and/or otherwise supporting one or more people, but should be thin enough that the mattress does not become unwieldy to transport or so large that sheets are difficult to secure in place about the mattress.

The core may also have a density of about 4 pounds to 8 pounds per cubic foot, and an IFD of about 28 to 65. The density may be varied based upon the size and number of foam pieces used, as well as the type of binder used. Core 12 has a top surface 14 and a bottom surface 16. One example showing how smaller foam pieces may be bonded to one another in order to form core 12 is shown in FIG. 5, and such methods of manufacture are described further below.

Coupled to bottom surface 16 may be a base layer 18. The two may be coupled together by glue, a bonding material or the like. Base layer 18 will typically be a piece of foam that is less dense than core 12 and may have a thickness in the range from about 0.25 inch to about 4 inches. In a particular embodiment, the base layer thickness may range from about 0.5 to about 2 inches, and may specifically be about one inch. The density may be in the range from about 1 pound per cubic foot to about 2 pounds per cubic foot, with an IFD of about 28 to about 70. Base layer 18 in some cases serves to help hold together the foam pieces in the matrix, thus increasing the life of the mattress.

Secured to top surface 16 is a cushion layer 20. One exemplary material that may be used to construct cushion layer is a visco-elastic foam, gel viscoelastic foam, air ventilated viscofoam with enhanced breathing properties, memory foam, down feathers, synthetic down alternative, latex, any combination thereof, or any other appropriate cushion-like surface that adds comfort and padding to the mattress. The cushion layer 20 may be formed as a combination of one or more comfort layers. The density of this cushion layer may be in the range from about 2 pounds per cubic foot to about 6 pounds per cubic foot. In a particular embodiment, the density may range from about 2 pounds per cubic foot to about 5 pounds per cubic foot, and may specifically be about 3 pounds per cubic foot or about 3.5 pounds per cubic foot. The height of the cushion layer may be about 1 inch to about 6 inches, more specifically from about 1 inch to about 5 inches, and more specifically, from about 2 inches to about 4.5 inches, and even more particularly, about 4.5 inches. The cushion layer may have an IFD rating of about 6 to about 18. FIGS. 1 and 2 show a single layer of visco-elastic foam, and FIGS. 5 and 6 show other embodiments having multiple layers of visco-elastic foam or other cushion-like material. Cushion layer may also be a combination of air insulated viscofoam with enhanced ventilating properties so that it breathes more and keeps the sleeper cooler.

The various layers may have different densities and or IFD ratings. As shown in FIG. 5, in a particular embodiment with the cushion layer formed of two layers, one layer 20 may be a visco-elastic memory foam and another layer 24 may be a second visco-elastic memory foam layer or a gel visco-elastic memory foam layer. The first lower visco-elastic memory foam layer may be about 3 to about 3.5 inches thick and may have a density of about 3 to about 3.5 pounds per cubic foot. The second upper visco-elastic memory foam layer or gel visco-elastic memory foam layer may be about 1 to about 1.5 inches thick. Providing two layers in the cushion layer can add additional comfort to the mattress.

A flame or fire retardant sock (referred to as an FR sock) may also be provided to enclose the completed mattress. Per regulations, this provides a covering for the mattress that meets an open flame standard. Alternatively, a flame retardant or resistant fiber layer may be provided below quilting if desired. A cover ticking 22 may be used to envelop the mattress. Ticking 22 comprises a fabric that is secured about the various layers. FIG. 4 shows a mattress that has been enveloped by a layer of ticking 22.

As shown in FIG. 3, various other layers may be provided on mattress 10 to change the look and feel of the mattress. These could be included beneath the ticking 22, such as with layer 24, or above ticking 22, such as in the case of an independent topper 26. These additional layers may be surface modified, such as convoluted. Examples of materials that may be used for the additional layers include latex, gel materials, fibrous spacer materials, that may optionally include a gel material, and the like. Also, various backing materials and fire resistant layers or materials may be used as well.

To construct core 12, multiple foam pieces are used. These may be of various shapes and sizes. Merely by way of example, these foam pieces may have a size in the range from about 0.25 inch by about 0.25 inch by about 0.25 inch to about 3 inches by about 3 inches by about 1 inch. Often, these may be pieces or remnants from other applications that can be repurposed rather than discarded. This often leads to the various sizes of pieces that may be used. For example, various pieces of remnant foams may be collected, then shredded down to smaller pieces. The individual pieces then need to be coated with a binder or resin, such as a polyurethane binder. This may be performed by feeding the pieces into a large container where the foam pieces are sprayed or otherwise mixed with the binder.

After the pieces are coated with the binder, they are fed into a mold. To facilitate the construction of a core that is to be used for a mattress, the foam pieces are placed within a rectangular mold. This mold may have various sizes depending on the desired size of the mattress. Merely by way of example, the mold may have a size in the range from about 60 inches by about 80 inches, with a height of about 3 feet to 4 feet. For larger mattresses, multiple cores may be bonded together. For example, two cores that are the size of a twin mattress could be bonded together at their sides to obtain the size and shape of a king sized mattress. A compression member that may be driven by a piston is used to compress the foam pieces to the desired density within the mold. Also, it will be appreciated that the density of the individual pieces will also contribute to the resulting density. The mold is then subjected to steam to cure the binder and allowed to cool. The resulting loaf is removed from the mold and has a rectangular shape. This loaf may be sliced into multiple layers in order to form separate cores. Additional timing to size may also be performed.

Mattresses made according to the various embodiments described herein were subjected to various tests in order to determine the firmness and fatigue resistance of the mattresses. The tests conducted are general protocol in the bedding industry. First, the firmness of the mattress is scanned and measured prior to any fatigue test. For this test, a 15″ circular plate is depressed into the bed in about nine locations, and the pounds of pressure required for the plate to press 75% into the mattress is measured. The plate then moves to 25% depression, which gives the IFD (indentation force deflection). Next, a rollator (which is a 3 foot, six-sided, 230 pounds log) rolls back and forth across center of mattress for about 10,000 cycles. The mattress rests 24 hours and is scanned, which electronically measures any loss/gain of height. The IFD test is conducted again as well. Additional cycles of 25,000 cycles, 50,000 cycles, 75,000 cycles and 100,000 cycles are run, repeating the rest, scan & IFD test. It is believed that about 100,000 cycles approximates 10 years of use.

Exemplary results for selected tests are outlined in the attached figures. FIG. 7 shows testing results from tests conducted on a mattress having the following parameters. FIG. 8 illustrates percentage changes in firmness of the mattress after such tests.

Mattress type: Green Choice Elegant 11″ (Core: 6.5 inches+1 inch support foam layer as base layer; cushion layer: 3.5 inches (1.5 inch air insulated viscofoam with ventilating properties +2 inches of regular viscofoam above core)

FIG. 9 shows exemplary results for selected tests conducted on a mattress having the following parameters. FIG. 10 illustrates percentage changes in firmness of the mattress after such tests.

Mattress type: Green Choice Bliss 10″ (Core: 4.5″ ES Core+1″ support foam; cushion layer: 3.5″ 3 lbs ViscoElas Memory Foam+1″ ViscoElas Memory Foam topper)

FIG. 11 shows exemplary results for selected tests conducted on a mattress having the following parameters. FIG. 12 illustrates percentage changes in firmness of the mattress after such tests.

Mattress type: Green Choice Relaxation 11″ (Core: 5.5″ ES Core+1″ support foam; cushion layer: 3″ 3 lbs ViscoElas Memory Foam+1.5″ Gel ViscoElas Memory Foam topper)

The invention has now been described in detail for purposes of clarity and understanding. However, it will be appreciated that certain changes and modifications may be practiced within the scope of the appended claims.

Claims

1. A mattress comprising:

a core comprising a matrix of foam pieces that are bonded together, wherein the core has a thickness in the range from about 1.5 inches to about 10 inches, a density of about 4 pounds to 8 pounds, and an IFD of about 28 to 65, the core having a top surface and a bottom surface; and

a cushion layer coupled to the top surface.

2. The mattress of claim 1, wherein the core thickness ranges from about 3 inches to about 8 inches'.

3. The mattress as in claim 1, wherein the cushion layer comprises a visco-elastic material.

4. The mattress as in claim 1, further comprising a top layer positioned above the cushion layer.

5. The mattress as in claim 1, further comprising a cover enveloping the core, the base layer and the cushion layer.

6. The mattress as in claim 5, wherein the cover is quilted.

7. The mattress as in claim 5, wherein the cover has flame retardant or flare resistant features.

8. The mattress as in claim 1, wherein the foam pieces comprise polyurethane, urethane, or a combination thereof

9. The mattress as in claim 1, further comprising a base layer coupled to the bottom surface of the core.

10. The mattress as in claim 9, wherein the base layer comprises a support foam layer.

11. A method for constructing a mattress, comprising:

forming a loaf by combining a plurality of foam pieces and a bonding material into a generally rectangular mold and applying heat, wherein the resulting loaf has a top, a bottom and four sides;

cutting a rectangular section from the loaf to form a core, wherein the rectangular section has a thickness in the range from about 1.5 inches to about 10 inches;

attaching a base layer to a bottom surface of the core;

attaching a cushion layer to a top surface of the core.

12. A method as in claim 11, further comprising placing a cover about the mattress.

13. A method as in claim 11, wherein the core has a density in the range from about 4 pounds to about 8 pounds and an IFD in the range from about 28 to about 65.

14. A method as in claim 11, wherein the bonding material comprises a polyurethane binder.

15. A method as in claim 11, wherein the plurality of foam pieces comprise repurposed pieces or remnants from other applications or from foam manufacturing runs that are otherwise unusable.