BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The invention relates to open flame resistant mattresses and mattress foundations
protected by a fire barrier comprised of microfiber fiberglass.
Description of the Related Art
[0002] The importance of preventing mattress fires in institutional settings has been recognized
for many years, and a number of standards for flame retardance of these mattresses
have been promulgated. A federal performance standard applicable to mattresses on
a nationwide basis is codified in 16 CFR Part 1632 (Standard for Flammability of Mattresses
and Mattress Pads), customarily referred to as the Cigarette Ignition Standard, the
entire contents of which are incorporated herein by reference. However, even when
mattresses meet the requirements of the Cigarette Ignition Standard, these can react
with volatile and potentially deadly results when exposed to open-flame and smoldering
ignition sources. The result can be a fire with sufficient energy to cause an average
size room to reach a state of total instantaneous combustion or flashover. The California
Bureau of Home Furnishings and Thermal Insulation has addressed the hazards associated
with the ignition of mattresses in public institutions with California Technical Bulletin
#129 (hereinafter 'TB 129'), published as a draft standard in 1992. It has since been
adopted as a voluntary consensus standard by the American Society of Testing and Materials
as ASTM E-1590 and the National Fire Protection Association (NFPA) as NFPA 267. (ASTM
E-1590 and NFPA 267 use essentially the same test protocol as TB 129 but contain no
failure criteria.) The standard has also been embodied in NFPA's Life Safety Code
2000, section 10.3.4, and in Underwriter's Laboratories' UL 1895.
[0003] Although hazards in public institutions have been addressed with standards based
on TB 129, the number of injuries and fatalities associated with residential fires
in which a mattress was the first item ignited or the mattress exacerbated the fire
event has led to efforts to reduce flammability of mattresses used in homes. One notable
event is the passage of Assembly Bill 603 in the California Legislature of Assembly.
The bill calls for virtually all mattresses and sleep surfaces sold in the State of
California, as of Jan. 1, 2004 to meet an open flame resistance standard. In addition,
the Consumer Products Safety Commission is currently developing new regulations for
further reducing mattress flammability beyond the level required by the Cigarette
Ignition Standards. This was announced recently in the Federal Register (Advance Notice
of Public Rule Making (ANPR) published Oct. 11, 2001)).
[0004] New standards for flammability of residential mattresses will require new materials
and methods of manufacturing these, as mattresses targeted for residential markets
differ significantly from those typically used in institutions. Institutional bedding
installations typically require only a mattress and no foundation; mattress may be
simply a solid core of polyurethane foam, which may be combustion modified to some
degree as well. Many of the components used in institutional mattresses and sleep
support surfaces, including fill materials and covering fabrics are subject to performance
testing according to test criteria such as NFPA 701 and California Technical Bulletin
No. 117.
[0005] In contrast to institutional bedding, residential sleep surfaces are typically covered
and filled with a number of potentially volatile components, including polyurethane
foam, highly combustible ticking fabrics, insulator padding, and pockets or cavities
of air that can serve to feed an ignition source such as a candle, match, lighter,
faulty electric socket, tipped over lamp or smoldering cigarette. For instance, pillow-top
constructions feature additional layers of filling materials contained in layers on
the panel surfaces, and set off aesthetically from the basic mattress design by gussets
or seam lines in the case of the box-top approach. Gussets create thin lines of highly
volatile fill materials and add more gaps and crevasses that can trap and concentrate
heat and flame. A crowned/convex shape for the sleep surface or mattress panel also
creates crevasses or voids between a mattress and foundation, again providing areas
that can trap heat and flames and concentrates these on small areas. Also, the presence
of a foundation does not provide an easy escape path for dissipation of heat across
and beyond the bottom of the mattress. Super heating in the air cavity within the
mattress and/or foundation can lead to what has been referred to as a flashover event.
[0006] One approach to reducing flammability of mattresses used in residential settings
has been to treat fabrics used in their construction with chemical flame retardants.
However, these chemical treatments may be objectionable because of distasteful odors
which are noticeable when in close contact with the materials, off-gassing obnoxious
elements, stiffness of the fabric caused by such treatments, which may compromise
the comfort of the finished mattress or mattress foundation, and the potential temporary
durability of such treatments, which may compromise the long term protection from
open-flame, smoldering ignition and radiant/thermal heat flux sources. Other attempts
to reducing flammability of fabrics have been only partly successful, and there are
no materials commercially available for use in mattress that can reduce flammability
of a sleep set including a mattress and foundation to a level where the requirements
of TB 129 can be met.
[0007] The use of fiberglass as a fire barrier material has been suggested. For example,
U.S. Pat. No. 4,504,991, to Klancnik, relates to a fire-resistant mattress that includes a flame-retardant composite.
The composite is a two-layered material, made up of a flame-retardant material that
forms a char when exposed to fire and a layer of high tensile strength material. The
flammable materials of the mattress are enclosed by the composite. In the single embodiment
disclosed, the composite is made up of a neoprene foam bonded to a fiberglass fabric.
[0008] U.S. Pat. No. 4,092,752, to Dougan, relates to a mattress enclosed with a flame-retardant polyurethane foam having an
optional layer of polyimide foam. The foam core is enclosed in a flame retardant cloth
or retardant ticking, e.g., fiberglass cloth.
[0009] U.S. Pat. No. 4,801,493 to Ferziger et al., describes coated fiberglass fabrics which are fire retardant. The chemically coated
fabric comprises a woven or non-woven fiberglass fabric base to which one or more
thin layers of a polymeric coating have been applied. The fiberglass fabric base is
inherently fire retardant.
[0010] See also
U.S. Pat. Nos. 4,866,799 and
6,823,548. Both of these patents relate to the use of a fire resistant barrier or shield in
a mattress. The barrier or shield can comprise fiberglass.
[0011] However, none of these solutions is capable of imparting sufficient and consistent
flame-retardant characteristics to the full breadth of styles and constructions of
bedding typically used in the home, that is, a comfortable mattress placed atop a
foundation, both containing a significant amount of flammable material. As a result,
there is a need for new materials to protect residential mattress sets from fire,
and especially for material in use in manufacturing mattress than can meet the more
stringent flammability standards expected to be imposed on the residential market,
such as TB 129. Also there is a need for providing comfortable bedding which is fire
resistant. This is particularly true when using fiberglass, which can often result
in itch.
SUMMARY OF THE INVENTION
[0012] The present invention provides a fire resistant layer for use in mattresses, and
other furniture, which layer is comprised of glass microfibers. The glass microfibers
are generally employed in a fire resistant layer strategically placed within the mattress
or other item. In mattresses, the layer will generally be placed as a shield against
an open flame reaching the core contents of the mattress, which are generally comprised
of highly flammable materials.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] The fire resistant layer can be a single layer of primarily microfiber fiberglass,
or a single layer of primarily microfiber fiberglass with a nonwoven or woven facer
on one side, or a "sandwich" of woven or nonwoven fabric, e.g. such as a needlepunched
or spunbond nonwoven, around a core of primarily microfiber fiberglass.
[0014] In a preferred embodiment, the fiberglass fire barrier layer of the invention will
be comprised primarily of microfibers of fiberglass having an average fiber diameter
between 0.2 microns and 6 microns, and more preferably less than 3 microns, and most
preferably less than 1.0 micron. The most preferred diameter is between 0.5 and 1.0
micron average fiber diameter. The smaller microfibers are preferred for reasons of
comfort. Biosoluble glass microfiber is also preferred.
[0015] The microfiber fiberglass nonwoven layer can be formed using a variety of conventional
nonwoven processes. These include, but are not limited to air-laid, dry-laid or wet-laid
processes. The processes form a fire-resistant nonwoven fabric. This fire-resistant
fabric can also contain between 0% and 60% by weight of polymer, natural and/or glass
fibers that are larger than 8 microns in diameter. It is preferred, however, that
the fabric be an all glass product, and not preferably an all micro-fiberglass product.
[0016] The fire-resistant nonwoven can be either bonded or unbonded. For bonding, an organic
binder, such as, but not limited to, urea formaldehyde, melamine or acrylic binders
can be used. Also, an inorganic binder, such as, but not limited to, the bonding action
of acid drying on glass fibers is an option. Unbonded fibers that are held together
by the tangling of the fibers either with or without one or two facers for added strength
or handleability can also be employed in another embodiment.
[0017] The fire resistant layer comprising the glass microfibers can further comprise a
woven or non-woven substrate. The substrate can be a needlepunched or spunbond nonwoven
fabric bonded on one or both sides of the fire resistant layer. These substrates can
add comfort, tensile and tear strength to the fire resistant layer. The substrate
can be of any suitable fiber, e.g., polyester.
[0018] The functionality of the fire-resistant nonwoven is to act as a barrier to inhibit
fire and heat from an open flame such as a candle, match, cigarette lighter or the
same from reaching the inside of the mattress. Typically the inside of a mattress
is made of highly flammable material such as foam that will burn quickly and at high
temperatures if exposed to an open flame and may spontaneously combust if enough heat
is added. As noted above, the functionality of the outside woven or nonwoven substrates
is to provide tensile and tear strength to allow the fire resistant layer fabric to
be more easily stitched into a mattress in a standard construction and as a comfort
layer to prohibit any potential skin irritation from operators during the manufacture
of a bedding mattress.
[0019] A typical design approach for residential mattresses is to localize comfort elements,
such as polyurethane foams and battings, in the sleep surface areas (panels), with
a minimum of fabric in the borders or sides. Accordingly, the fire barrier fabric
comprising the glass microfibers according to the present invention at least partially
encloses the core of the mattress, and the core may be fully enclosed, if desired,
as flame retardant performance may be achieved without loft or thickness being so
high as to hinder the ability of the mattress manufacturer to completely encapsulate
the fuel load with the fire barrier fabric. In addition, the weight of the fire barrier
layer and the composition of any outside substrate may be varied in order to address
the burning and combustion challenges presented by a variety of mattress and mattress
foundation designs. The fire barrier fabric having different compositions and weight
may be used to cover different areas of the mattress or mattress foundation. For example,
lighter weight and lower cost versions may be used as barriers for the horizontal
surface area that is the panel or mattress top, while heavier weight and higher cost
versions may be used to protect vertical surfaces, that is the borders or sides of
the mattress for foundation. In general, design and financial resources for raw materials
and assembly costs may be targeted to areas of the mattress and foundation that require
a greater investment for fire protection. Also, the fire barrier fabric for the panel
and/or border may be joined at the tape edge of the mattress with sewing thread specifically
designed to withstand ignition, typically para-aramid or fiberglass sewing thread.
[0020] The fire barrier fabric may be placed under or disposed beneath a mattress ticking,
but is generally never placed as the outermost layer. The fire barrier fabric may
be simply placed adjacent to or in contact with the ticking using flame-retardant
thread, or it may be bonded or attached to it. In particular, the fire barrier fabric
may be conveniently quilted to the ticking, as mattresses for the residential market
typically have decorative patterns stitched in the cover fabric or filling materials.
This can be of benefit to mattress manufacturers, and only one feed position on quilting
equipment may be required to add the fire barrier fabric during the quilting operation.
Fire-retardant thread composed of the resistant fibers such as fiberglass or para-aramid
may be used in the quilting operation.
[0021] The fire barrier fabric may also be designed to address variable flammability of
any exterior cover by including fibers in that exterior woven or nonwoven substrates
that provide structure to the char formed therefrom. This includes the stitching which
may result in a point of weakness. Therefore, fibers that yield a char having structural
integrity may be used to promote survival of the flame barrier.
[0022] Having thus described the invention in detail, it will be understood that such detail
need not be strictly adhered to, but that additional changes and modifications may
suggest themselves to one skilled in the art, all falling within the scope of the
invention as defined by the subjoined claims.
1. A mattress comprising a fire resistant layer of glass microfiber having an average
diameter of less than 6 microns.
2. The mattress of claim 1, wherein the glass microfiber has an average diameter of less
than 3 microns.
3. The mattress of claim 1, wherein the glass microfiber has an average diameter no greater
than 1.0 micron.
4. The mattress of claim 1, wherein the fire resistant layer further comprises a woven
or non-woven fabric on one or both sides of the layer.
5. The mattress of claim 4, wherein the fire resistant layer comprises a spunbond polyester
fabric on at least one side.
6. The mattress of claim 4, wherein the fire resistant layer comprises a sandwich of
woven or nonwoven fabric around a core comprised of glass microfiber.
7. The mattress of claim 5, wherein the polymer fabric is comprised of a polyester or
polypropylene material.
8. The mattress of claim 5, wherein the polymer fabric is comprised of a spunbond polyester
material.
9. Furniture comprising a fire resistant layer of glass microfiber having an average
diameter of less than 6 microns.
10. The furniture of claim 9, wherein the glass microfiber has an average diameter no
greater than 1.0 micron.