U.S. patent application number 11/267492 was filed with the patent office on 2006-03-09 for fire resistant fabric composite, process for fire-blocking a mattress and mattress set, and a mattress and mattress set fire-blocked thereby.
Invention is credited to Herman Hans Forsten, Warren F. Knoff, William E. III Younts.
Application Number | 20060048302 11/267492 |
Document ID | / |
Family ID | 34103761 |
Filed Date | 2006-03-09 |
United States Patent
Application |
20060048302 |
Kind Code |
A1 |
Forsten; Herman Hans ; et
al. |
March 9, 2006 |
Fire resistant fabric composite, process for fire-blocking a
mattress and mattress set, and a mattress and mattress set
fire-blocked thereby
Abstract
This invention relates to a fabric composite for use in
fire-blocking a mattress, a fire-blocked mattress set, and a
process for fire-blocking mattresses; the fabric composite
comprising, in order, (a) sacrificial outer ticking, (b)
sacrificial cushioning material, and (c) fire-blocking fabric, the
fire-blocking fabric being a single layer of nonwoven fabric
comprising at least 0.5 ounces per square yard (17 grams per square
meter) of a cellulose fiber that retains at least 10 percent of its
fiber weight when heated in air to 700 C at a rate of 20 degrees C.
per minute, and at least 0.5 ounces per square yard (17 grams per
square meter) of a heat-resistant fiber. Mattress sets fire-blocked
with this fabric composite have a peak heat release rate of less
than 150 kilowatts within 30 minutes, preferably less that 150
kilowatts within 60 minutes, and a total heat release of less than
25 megajoules within 10 minutes when tested according to Technical
Bulletin 603 of the State of California.
Inventors: |
Forsten; Herman Hans;
(Williamsburg, VA) ; Knoff; Warren F.; (Richmond,
VA) ; Younts; William E. III; (Fort Mill,
SC) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY;LEGAL PATENT RECORDS CENTER
BARLEY MILL PLAZA 25/1128
4417 LANCASTER PIKE
WILMINGTON
DE
19805
US
|
Family ID: |
34103761 |
Appl. No.: |
11/267492 |
Filed: |
November 4, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10630081 |
Jul 29, 2003 |
|
|
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11267492 |
Nov 4, 2005 |
|
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Current U.S.
Class: |
5/698 ;
5/954 |
Current CPC
Class: |
Y10T 442/647 20150401;
B32B 5/024 20130101; A47C 31/001 20130101; B32B 2307/3065 20130101;
Y10T 442/651 20150401; Y10T 442/696 20150401; B32B 5/18 20130101;
B32B 5/022 20130101; B32B 5/26 20130101; Y10T 442/698 20150401 |
Class at
Publication: |
005/698 ;
005/954 |
International
Class: |
A47C 17/00 20060101
A47C017/00 |
Claims
1-16. (canceled)
17. A mattress resistant to an open flame comprising a fabric
composite containing in order: (a) sacrificial outer ticking, (b)
sacrificial cushioning material, and (c) fire-blocking fabric, the
fire-blocking fabric being a single layer of nonwoven fabric
comprising at least 0.5 ounces per square yard (17 grams per square
meter) of a cellulose fiber that retains at least 10 percent of its
fiber weight when heated in air to 700 C at a rate of 20 degrees C.
per minute, and at least 0.5 ounces per square yarn (17 grams per
square meter) of a heat-resistant fiber. with the provisos: (i)
only a single layer is employed in the fireblocking fabric of (c)
and (ii) only a single layer of fabric is employed for fireblocking
the mattress.
18. The mattress of claim 17 wherein the fabric composite is
located in a panel of the mattress.
19. The mattress of claim 17 wherein the fabric composite is
located in a border of the mattress.
20. The mattress of claim 17 wherein the fabric composite further
comprises seams having fire resistant thread stitching.
21. A mattress resistant to an open flame comprising the fabric
composite of claim 17 wherein the cellulose fiber retains at least
90 percent of its fiber weight.
22. The mattress of claim 21 wherein the fabric composite is
located in a panel of the mattress.
23. The mattress of claim 21 wherein the fabric composite is
located in a border of the mattress.
24. The mattress of claim 21 wherein the fabric composite further
comprises seams having fire resistant thread stitching.
25. A mattress resistant to open flame comprising the fabric
composite of claim 17. wherein the heat resistant fiber is a
poly(paraphenylene terephthalamide) fiber and the cellulose fiber
(X) and heat resistant fiber (Y) being present in the fire-blocking
fabric in a weight ratio expressed by the equation:
Y>/=-0.14X+1.3.
26. A mattress set resistance to an open flame comprising a
mattress of claim 17 and a mattress foundation.
27. A mattress set resistance to an open flame comprising a
mattress of claim 21 and a mattress foundation.
28. A mattress set resistance to an open flame comprising a
mattress of claim 25 and a mattress foundation.
29. A mattress set resistant to an open flame comprising a mattress
and a mattress foundation: the mattress comprising a fabric
composite and a mattress core, the fabric composite comprising in
order: (a) sacrificial outer ticking, (b) sacrificial cushioning
material, and (c) a single layer nonwoven fire-blocking fabric, the
mattress foundation comprising a single layer nonwoven
fire-blocking fabric and a support structure, wherein the mattress
set has a peak heat release rate of less than 150 kilowatts within
30 minutes and a total heat release of less than 25 megajoules in
the first 10 minutes when tested according to Technical Bulletin
603 of the State of California. with the provisos: (iii) only a
single layer is employed in the fireblocking fabric of (c) and (iv)
only a single layer of fabric is employed for fireblocking the
mattress.
30. The mattress set of claim 26 wherein the single layer nonwoven
fire-blocking fabric comprises at least 0.5 ounces per square yard
(17 grams per square meter) of a heat resistant fiber, the nonwoven
fabric having a basis weight of at least 2.5 ounces per square yard
(85 grams per square meter).
31. The mattress set of claim 27 wherein the heat resistant fiber
is an organic fiber that retains 90 percent of its fiber weight
when heated in air to 500 C at a rate of 20 degrees C. per
minute.
32. The mattress set of claim 27 wherein the heat resistant fiber
comprises a polymer selected from the group of para-aramid,
polybenzazole, polybenzimidazole, and polyimide.
33. The mattress set of claim 27 wherein the heat resistant fiber
is a poly(paraphenylene terephthalamide) fiber and the nonwoven
fire-blocking layer includes a viscose fiber containing silicic
acid, the viscose fiber (X) and heat resistant fiber (Y) being
present in the fire-blocking fabric in a weight ratio expressed by
the equation Y>/=-0.14X+1.3.
34. The mattress set of claim 18 wherein the mattress set has a
peak heat release rate of less than 150 kilowatts within 60 minutes
and a total heat release of less than 25 megajoules in the first 10
minutes when tested according to Technical Bulletin 603 of the
State of California.
35. The mattress set of claim 31 wherein the single layer nonwoven
fire-blocking fabric comprises at least 0.5 ounces per square yard
(17 grams per square meter) of a heat resistant fiber, the nonwoven
fabric having a basis weight of at least 2.5 ounces per square yard
(85 grams per square meter).
36. The mattress set of claim 32 wherein the heat resistant fiber
is an organic fiber that retains 90 percent of its fiber weight
when heated in air to 500 C at a rate of 20 degrees C. per
minute.
37. The mattress set of claim 32 wherein the heat resistant fiber
comprises a polymer selected from the group of para-aramid,
polybenzazole, polybenzimidazole, and polyimide.
38. The mattress set of claim 32 wherein the heat resistant fiber
is a poly(paraphenylene terephthalamide) fiber and the nonwoven
fire-blocking layer includes a viscose fiber containing silicic
acid, the viscose fiber (X) and heat resistant fiber (Y) being
present in the fire-blocking fabric in a weight ratio expressed by
the equation Y>/=-0.14X+1.4.
39. A process for fire-blocking a mattress while retaining the
aesthetics of the mattress cushioning material, the mattress
having, in order, ticking, cushioning material, and a mattress
core, the process comprising: (a) incorporating into the mattress a
fire-blocking fabric between the cushioning material and the
mattress core, (b) the fire-blocking fabric being a single layer of
nonwoven fabric comprising at least 0.5 ounce per square yard (17
grams per square meter) of a cellulose fiber that retains at least
10 percent of its fiber weight when heated in air to 700 C at a
rate of 20 degrees C. per minute and at least 0.5 ounces per square
yard (17 grams per square meter) of a heat-resistant fiber. with
the provisos: (v) only a single layer is employed in the
fireblocking fabric set forth in (a) and (b) and (vi) only a single
layer of fabric is employed for fireblocking the mattress.
40. The process of claim 34 wherein the heat resistant fiber is an
organic fiber that retains 90 percent of its fiber weight when
heated in air to 500 C at a rate of 20 degrees C. per minute.
41. The process of claim 34 wherein the heat-resistant fiber
comprises a polymer selected from the group of para-aramid,
polybenzazole, polybenzimidazole, and polyimide.
42. The process of claim 36 wherein the para-aramid is
poly(paraphenylene terephthalamide).
43. The process of claim 34 wherein the heat resistant fiber is a
poly(paraphenylene terephthalamide) fiber and the cellulose fiber
is a viscose fiber containing silicic acid, the viscose fiber (X)
and poly(paraphenylene terephthalamide) fiber (Y) being present in
the fire-blocking fabric in a weight ratio expressed by the
equation Y>/=-0.14X+1.4.
44. The process of claim 34 wherein the fire-blocking fabric
further comprises an off gassing material that releases a flame
suppressing gas when burned.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a fabric composite for use in
fire-blocking a mattress, a fire-blocked mattress set, and a
process for fire-blocking mattresses. Such mattress sets have a
peak heat release rate of less than 150 kilowatts within 60 minutes
and a total heat release of less than 25 megajoules within 10
minutes when tested according to Technical Bulletin 603 of the
State of California.
[0003] 2. Description of Related Art
[0004] The State of California has led the drive to regulate and
reduce the flammability of mattresses and mattress sets in an
attempt to reduce the number of lives lost in household, hotel, and
Institutional fires. In particular, the Bureau of Home Furnishings
and Thermal Insulation of the Department of Consumer Affairs of the
State of California issued Technical Bulletin 603 "Requirements and
Test Procedure for Resistance of a Residential Mattress/Box Spring
Set to a Large Open-Flame" to quantify the flammability performance
of mattress sets. * Mattresses normally contain a mattress core
covered by a cushioning material that is in turn covered with an
outer fabric ticking. Most cushioning material is made from foam or
fiber materials that will burn when exposed to an open flame. One
useful method of fire-blocking foam cushions, particularly airplane
seats, is disclosed in U.S. Pat. No. 4,750,443 to Blaustein, et
al., wherein three to seven layers of flame resistant fabrics are
used underneath the covering fabric of the seat to encase the foam.
To the degree required per the aircraft seat flammability test
method, these fire-blocked cushions withstand a flame jet impinging
oh the cushion and prevent the entire cushion from being engulfed
by the flame or continuing to burn after the flame jet is
removed.
[0005] U.S. Pat. Nos. 6,132,476; 6,547,835; and 5,609,950 disclose
fabric blends of inherently flame resistant fibers and cellulosic
fibers having increased flame resistance; the fabric can contain an
additional fire retardant that is added, for example, as an
additive in a dyeing step. Because of the low content of inorganic
material the flame resistant cellulose fiber disclosed in these
references does not retain an adequate percentage of their fiber
weight when exposed to high temperatures.
[0006] Mattresses are sold by a consumer's initial impression of
support and comfort and, therefore, mattresses normally contain, in
addition to any supporting foam in the mattress core, cushioning
material made from light density fibrous battings or foams, or a
combination of both, that provide a surface cushioning effect. This
tactile cushioning effect is highly desired by the consumer. The
cushioning material is normally stitched and acts like a pillow
above the mattress core, providing very tactile cushioning, the
type that can be readily discerned by simply touching or running
one's hand across the mattress. Attempts to encase all the
flammable materials in a mattress with a fire-blocking fabric in a
manner similar to that used for airplane seats, that is, by
inserting appropriate fire-blocking layers underneath the ticking
to encase all the battinging and/or the foam, compress and restrain
the cushioning material and severely limit the cushioning effect,
giving the mattress poor initial tactile aesthetics. In addition,
the use of multiple fire-blocking layers can also add stiffness or
restrain the give of the mattress core, affecting overall comfort.
Therefore, what is needed is a way to fire-block a mattress while
retaining excellent initial aesthetics of the mattress, including
the tactile aesthetics of the cushioning material.
SUMMARY OF THE INVENTION
[0007] This invention is, related to a fabric composite resistant
to an open flame comprising, in order, sacrificial outer ticking,
sacrificial cushioning material, and fire-blocking fabric, the
fire-blocking fabric being a single layer of nonwoven fabric
comprising at least 0.5 ounces per square yard (17 grams per square
meter) of a cellulose fiber that retains at least 10 percent of its
fiber weight when heated in air to 700 C at a rate of 20 degrees C.
per minute, and at least 0.5 ounces per square yard (17 grams per
square meter) of a heat-resistant fiber. In one embodiment of this
invention, the cellulose fiber is a viscose fiber containing
silicic acid, and the heat-resistant fiber is a poly(paraphenylene
terephthalamide fiber, and the viscose fiber (X) and heat resistant
fiber (Y) are present in the fire-blocking fabric in a weight ratio
expressed by the equation: Y>/=-0.14X+1.4.
[0008] This invention is also related to a mattress set resistant
to an open flame comprising a mattress and a mattress foundation:
the mattress comprising a fabric composite and a mattress core, the
fabric composite comprising in order: i) sacrificial outer ticking,
ii) sacrificial cushioning material, and iii) a single layer
nonwoven fire-blocking fabric, and the mattress foundation
comprising a single layer nonwoven fire-blocking fabric and a
support structure, wherein the mattress set has a peak heat release
rate of less than 150 kilowatts within 30 minutes and a total heat
release of less than 25 megajoules in the first 10 minutes when
tested according to Technical Bulletin 603 of the State of
California. In one embodiment, the mattress set has a peak heart
release rate of less than 150 kilowatts within 60 minutes and a
total heat release of less than 25 megajoules in the first 10
minutes when tested according to Technical Bulletin 603 of the
State of California.
[0009] This invention is also related to a process for
fire-blocking a mattress having, in order, ticking, cushioning
material, and a mattress core, the process comprising incorporating
into the mattress a fire-blocking fabric between the cushioning
material and the mattress core; the fire-blocking fabric being a
single layer of nonwoven fabric comprising least 0.5 ounce per
square yard (17 grams per square meter) of a cellulose fiber that
retains at least 10 percent of its fiber weight when heated in air
to 700 C at a rate of 20 degrees C. per minute and at least 0.5
ounces per square yard (17 grams per square meter) of a
heat-resistant fiber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 illustrates, in a simplified manner, the fabric
composite of this invention.
[0011] FIG. 2 illustrates a range of compositions for the
fire-blocking fabric used in this invention.
[0012] FIG. 3 illustrates a preferred range of compositions for the
fire-blocking fabric used in this invention.
[0013] FIG. 4 illustrates a simplified cross section of the
fire-blocked mattress of this invention.
[0014] FIG. 5 illustrates a cut-away view of the fire-blocked
mattress of this invention, showing in a simplified manner the
fabric composite, cushioning foam, and mattress internals.
[0015] FIG. 6 illustrates a simplified cross section of one
possible embodiment of a fire-blocked foundation of this
Invention.
[0016] FIG. 7 illustrates a simplified cross section of one
possible embodiment of a fire-blocked foundation of this invention
having a different fabric top face.
[0017] FIG. 8 illustrates, in a simplified manner, the arrangement
of burners, the mattress and foundation used to test the burn
performance of a mattress and mattress set of this invention.
[0018] FIG. 9 illustrates, in a simplified manner, the offset of
the arrangement of burners used to burn the mattress and mattress
set of this invention.
DETAILS OF THE INVENTION
[0019] This invention is directed to fabric composite for use with
mattresses. This fabric composite allows for various external
surface affects to be created for the mattress, such as a quilted
pillow surface or other soft, deformable surface, which insures the
mattress of this invention has essentially the same feel to the
touch as a mattress not containing a fire-blocking layer.
[0020] This invention is also directed to a fire-blocked mattress
that incorporates the fabric composite. The fabric composite
comprises, in order, outer fabric ticking, cushioning material, and
fire-blocking fabric. The term sacrificial fabric as employed in
conjunction with sacrificial outer ticking and sacrificial
cushioning material denotes the ability of the fabric to burn when
exposed to a flame. Although a fire-retardant chemical may be
introduced in a sacrificial fabric, such incorporation is not
necessary. The ticking and cushioning material become sacrificial
layers if the mattress is burned. That is, they are allowed to burn
when the mattress is exposed to a flame. The inventors of the
present invention have found that such materials may be allowed to
burn as long as the quantity of the available fuel contributed by
the ticking and cushioning material is limited and the
fire-blocking fabric is constructed of appropriate materials. The
fire-blocking fabric performs certain functions when the mattress
set is burned, including (1 ) protecting the mattress core along
with any foams therein from the impinging flame and the burning
batting and ticking, and (2) resisting the propagation of the flame
along the surface of the mattress. The actual construction
technique for the fabric composite is not critical as long as the
materials are assembled in order with the ticking on the outside,
the cushioning material in the center and then the fire-blocking
fabric. Preferably, the fabric composite can be made in a separate
step and then placed over and attached to the mattress core,
however, it is also possible that the individual layers may be
placed separately over the mattress core and assembled on the
mattress core.
[0021] This invention is further directed to a mattress set
resistant to an open flame comprising a mattress and a mattress
foundation wherein the mattress includes a fabric composite and a
mattress core, the fabric composite comprising, in order, a
sacrificial outer ticking, a sacrificial cushioning material, and a
single layer nonwoven fire-blocking fabric. The mattress foundation
can also include the fabric composite. The mattress set has a peak
heat release rate of less than 150 kilowatts within the first 30
minutes of the test, and preferably less than 150 kilowatts within
the first 60 minutes of the test, when tested according to
Technical Bulletin 603 of the State of California. Additionally,
the mattress set has a total heat release of less than 25
megajoules within 10 minutes when tested according to Technical
Bulletin 603.
Fabric Composite
[0022] FIG. 1 is a simplified representation of a cutout of the
fabric composite of this invention with the individual parts not
drawn to scale but expanded for clarity. Fabric composite 10 is
shown with ticking 11 combined with cushioning material 12.
Adjacent to the cushioning material is fire-blocking fabric 14.
This figure illustrates a quilt-type pattern with stitches 15
forming a pillowed surface in the ticking and cushioning
material.
Sacrificial Ticking
[0023] The outer surface of the fabric composite 10 is covered by
ticking 11. Such fabrics are normally very durable woven or knit
fabrics, utilizing any number of weaves, and tend to have basis
weights in the range of 2 to 8 ounces per square yard (68 to 271
grams per square meter). Typical ticking fabrics may contain but
are not limited to cotton, polyester fibers, or rayon fibers. The
ticking is normally stitched to the cushioning material and the
fire-blocking fabric, making quilt-like areas to create pillow-like
projections on the outer face of the fabric composite or mattress.
In addition, the seams of ticking and/or the fabric composite at
the edges of the mattress may be taped and sewn to provide addition
seam strength at these areas. It is preferred that the sewing
thread used to stitch the ticking at the seams and the material
used in the edge tapes be made from a flame resistant material. The
preferred flame resistant material for stitching is an aramid
thread made from aramid fiber and the preferred aramid is
poly(paraphenylene terephthalamide).
Sacrificial Cushioning Material
[0024] The fabric composite 10 of this invention contains a
cushioning material 12 to provide additional initial comfort. This
cushioning material is in addition to any supporting foam in the
mattress core. The cushioning material may include one or more
light density fibrous batting or foams, or a combination thereof
that provide the surface effect that is highly desired by the
consumer. The batting and/or foams acts like a pillow underneath
the ticking, providing very tactile cushioning, the type that can
be readily discerned by simply touching or running one's hand
across the mattress. While not intended to be limiting, if the
cushioning material is a fibrous batting, such batting may include
a vertically pleated structure as disclosed in, for example, in PCT
Publication WO 2003049581 or a batting of fibers as disclosed for
example in U.S. Pat. No. 3,118,750.
[0025] The cushioning material adds potential fuel to the fabric
composite and the maximum allowable basis weight of the cushioning
material used in the fabric composite depends on a number of
parameters. The heat of combustion of the cushioning material and,
the burn rate are the most critical of these parameters. For
typical polyester (PET) batting widely used in the bedding
industry, the heat of combustion is about 21.6 megajoules per
kilogram (page V/113 "Handbook of Polymers" Fourth Edition, John
Wiley & Sons, Inc. 1999). For a standard twin size mattress the
top panel is about 2.4 square yards (2.6 square meters), and the
total heat of combustion from a 1 ounce per square foot (305 grams
per square meter) polyester batting on that top panel is about
13.25 megajoules. The burn pattern on the top panel typically
radiates outward from the location of the burner at a rate at which
the cushioning layer on the top panel is completely consumed within
the first 30 minutes of the test. The above observations and facts
lead to a simple model of heat release in which the heat release
rate starts at approximately zero and increases linearly with time.
Within these assumptions, the following table can be calculated.
TABLE-US-00001 TABLE 1 Computed Heat Release for Polyester Batting
in Mattresses PET Basis THR at 10 THR at 30 weight oz/ft.sup.2
PHRR, kW min, MJ min, MJ 1 14.8 1.5 13.3 2 29.5 2.9 29.5 4 59.0 5.9
53.0 6 88.5 8.8 88.5 10 147.6 14.7 132.5 12 177.1 17.7 159.1
PHRR--Peak Heat Release Rate THR--Total Heat Release
[0026] Table 1 shows that, in the absence of all other sources of
heat, the maximum allowable basis weight of a typical cushioning
layer is around 10 oz/yd.sup.2 (339 g/m.sup.2). This corresponds to
a total heat of combustion of 130 MJ/yd.sup.2 (155 MJ/m.sup.2).
Above this value the peak heat release rate is predicted to exceed
the 150 kW allowable maximum. Therefore, the total combined heat of
combustion of the sacrificial cushioning layer and any ticking
should not exceed about 130 MJ/yd.sup.2 (155 MJ/m.sup.2). While
fiber batting has been used as an example, the same total combined
heat of combustion would apply if the cushioning layer was foam or
a combination of foam and fiber batting.
Fire-Blocking Fabric
[0027] The fire-blocking fabric positioned underneath the ticking
and cushioning material is a single layer nonwoven fabric
preferably comprised of at least 0.5 ounces per square yard (17
grams per square meter) of a cellulose fiber that retains at least
10 percent of its fiber weight when heated in air to 700 C at a
rate of 20 degrees C. per minute, and at least 0.5 ounces per
square yard (17 grams per square meter) of heat resistant fiber.
The nonwoven fire-blocking fabric used in this invention has a
basis weight of at least 2.5 ounces per square yard (85 grams per
square meter). Single layer nonwoven fabrics having basis weights
of less than that amount do not provide adequate fire-blocking
performance. The maximum practical basis weight of the nonwoven
fire-blocking fabric of this invention is in the range of 7 ounces
per square yard. Heavier weight fabrics still provide protection,
however, with additional basis weight there is little improvement
in fire retarding performance. Nonwoven fabrics having this
composition and basis weight can be used as the sole fire-blocking
component for a mattress or a mattress set comprising a mattress
and foundation.
[0028] The nonwoven fire-blocking fabric can be made by
conventional nonwoven sheet forming processes, including processes
for making air-laid nonwovens or wet-laid nonwovens, and such
formed sheets can be consolidated into fabrics via spunlacing,
hydrolacing, needlepunching, or other processes which can generate
a nonwoven sheet. The spunlaced processes disclosed in U.S. Pat.
No. 3,508,308 and U.S. Pat. No. 3,797,074; and the needlepunching
processes disclosed in U.S. Pat. No. 2,910,763 and U.S. Pat. No.
3,684,284 are examples of methods well-known in the art that are
useful in the manufacture of the nonwoven fabrics. The preferred
nonwoven fabrics of this invention are air-laid spunlaced or
hydrolaced nonwovens where high pressure water jets are used to
entangle fibers into a cohesive sheet;.
Cellulose Fiber
[0029] Cellulose fiber useful in this invention is a char-forming
cellulose fiber. By char-forming, it is meant the cellulose fiber
retains at least 10 percent of its weight when heated in air to 700
C at a rate of 20 degrees C. per minute. Such cellulose fibers
preferably have 10 percent inorganic compounds incorporated into
the fibers. Such fibers, and methods for making such fibers, are
generally disclosed in U.S. Pat. No. 3,565,749 and British Pat. No.
GB 1,064,271. A preferred char-forming cellulose fiber for this
invention is a viscose fiber containing silicon dioxide in the form
of a polysilicic acid with aluminum silicate sites. Such fibers,
and methods for making such fibers are generally disclosed in U.S.
Pat. Nos. 5,417,752 and PCT Pat. Appl. WO 9217629. Viscose fiber
containing silicic acid and having approximately 31 (+/-3) percent
inorganic material is sold under the trademark Visil.RTM. by Sateri
Oy Company of Finland. The char-forming fibers of this invention,
when incorporated into the nonwoven fabric, provide adequate
fire-blocking performance without the need for the fabric to be
treated with additional flame-retardant additives or
topically-applied flame retardant compounds.
Heat Resistant Fiber
[0030] The single layer nonwoven fabric contains a least 0.5 ounces
per square yard of a heat resistant fiber and the fiber is
preferably an organic fiber. By "heat resistant" it is meant that
the fiber preferably retains 90 percent of its fiber weight when
heated in air to 500 C at a rate of 20 degrees C. per minute. Such
fibers are normally flame resistant, meaning the fiber or a fabric
made from the fiber has a Limiting Oxygen Index (LOI) such that the
fiber or fabric will not support a flame in air, the preferred LOI
range being greater than 26. The preferred fibers do not
excessively shrink when exposed to a flame, that is, the length of
the fiber will not significantly shorten when exposed to flame.
Fabrics containing 0.5 ounces per square yard (17 grams per square
meter) of an organic fiber that retains 90 percent of its fiber
weight when heated in air to 500 C at a rate of 20 degrees C. per
minute tend to have limited amount of cracks and openings when
burned by an impinging flame.
[0031] Heat resistant and stable fibers useful in the nonwoven
fire-blocking fabric of this invention include fiber made from
para-aramid, polybenzazole, polybenzimidazole, and polyimide
polymer. The preferred heat resistant fiber is made from
para-aramid polymer.
[0032] As used herein, "aramid" is meant a polyamide wherein at
least 85% of the amide (--CONH--) linkages are attached directly to
two aromatic rings. Additives can be used with the aramid. In fact,
it has been found that up to as much as 10 percent, by weight, of
other polymeric material can be blended with the aramid or that
copolymers can be used having as much as 10 percent of other
diamine substituted for the diamine of the aramid or as much as 10
percent of other diacid chloride substituted for the diacid
chloride of the aramid. In the practice of this invention, the
preferred para-aramid is poly(paraphenylene terephthalamide).
Methods for making para-aramid fibers useful in this invention are
generally disclosed in, for example, U.S. Pat. Nos. 3,869,430;
3,869,429; and 3,767,756. Such aromatic polyamide organic fibers
and various forms of these fibers are available from DuPont
Company, Wilmington, Del. under the trademark Keviar.RTM.
fibers.
[0033] Commercially available polybenzazole fibers useful in this
invention include Zylon.RTM. PBO-AS
(Poly(p-phenylene-2,6-benzobisoxazole) fiber, Zylon.RTM. PBO-HM
(Poly(p-phenylene-2,6-benzobisoxazole)) fiber, available from
Toyobo, Japan. Commercially available polybenzimidazole fibers
useful in this invention include PBI.RTM. fiber available from
Celanese Acetate LLC. Commercially available polyimide fibers
useful in this invention include P-84.RTM. fiber available from
LaPlace Chemical.
Useful Combinations of Cellulose and Heat Resistant Fibers
[0034] One fire-blocking fabric useful in the fabric composite of
this invention comprises at least 0.5 ounces per square yard (17
grams per square meter) of a viscose fiber containing silicic acid,
and at least 0.5 ounces per square yard (17 grams per square meter)
of a poly(paraphenylene terephthalamide fiber; the viscose fiber
(X) and poly(paraphenylene terephthalamide) fiber (Y) being present
in a weight ratio expressed by the equation: Y>/=-0.14X+1.3
[0035] This area is represented by the area above the line in FIG.
2. Nonwoven fabric having the composition and the basis weights
shown by this area can be used as a single layer as the sole
fire-blocking component in the fabric composite, mattress and
mattress set of this invention. Mattress sets that contain the
fabric composite having the fire-blocking fabric so defined will
have, when burned according to the California method, a peak heat
release of less than 150 kilowatts within 30 minutes. This
eliminates the need for multiple layers of fire-blocking fabrics
that could add unacceptable bulk and/or stiffness to the
mattress.
[0036] A more preferred fire-blocking fabric useful in the fabric
composite of this invention will have a composition expressed by
the equation: Y>/=-0.14X+1.4
[0037] This area is represented by the area above the line in FIG.
3. Mattress sets that contain the fabric composite having the
fire-blocking fabric so defined will have, when burned according to
the California method, a peak heat release of less than 150
kilowatts within 60 minutes.
[0038] The nonwoven fire-blocking fabric used in this invention can
include, in addition, an off gassing material that releases a flame
suppressing gas when burned. The preferred off gassing material are
fibers made from halogen-containing polymers, such as modacrylic
fiber or polyvinylchloride fibers. These polymers release
chlorine-containing gases when burned. Up to 4 ounces per square
yard (136 grams per square meter) of such materials can be added to
the single layer nonwoven fabric. Useful modacrylic fibers include,
but are not limited to, those disclosed in U.S. Pat. No.
5,506,042.
Mattresses
[0039] FIG. 4 is a simplified representation of a mattress of this
invention, not drawn to scale for clarity. A cross section of
mattress 20 is shown having the complete periphery covered by
fabric composite 10. The top and bottom faces of the mattress,
normally called the panels of the mattress, are designated by 25.
The sides-of the mattress, normally called the borders of the
mattress, are designated by 26. Inside the fabric composite 10 is a
layer of supporting foam 22, and in this case the supporting foam
completely encases the mattress internals 21. FIG. 5 shows a
cut-away view of mattress 20 with the fire-blocking fabric
composite 10, supporting foam 22, and mattress internals 21.
[0040] For the purposes herein the mattress core is meant to
include any supporting foams 22 along with mattress internals 21.
The mattress internals are intended to include the mechanical
structure of the mattress, such as supporting beams and springs and
associated wrappings. Such internals can also include additional
foam, or combinations of foams and battings. The mattress core may
also be only foam or other support materials, such as an air or
liquid bladder with or without supporting foam, in the place of
springs and other mechanical means of support.
[0041] Supporting foam 22 as discussed herein is a part of the
mattress core and includes foams used to provide most of the
support comfort of the mattress. Normally such foams cover only the
panels of the mattress internals, however, the mattress internals
may be totally enclosed. Fire-blocking of the mattress is done in
large part to prevent the supporting foam from being ignited, or if
the foam is ignited, to help suppress spread of the flame in the
supporting foam.
[0042] The fabric composite of the this invention is useful to
fire-block the panels and/or the borders of the mattress, and
different amounts of cushioning material may be used in the borders
versus the panel of the mattress. To totally fire-block the
mattress the fire-blocking should be incorporated into all panels
and borders of the mattress. This allows the mattress to be turned
by the owner so that both sides of the mattress can be used,
without losing any of the fire-blocking qualities.
Mattress Set
[0043] The fabric composite can also be used to fire-block a
mattress set comprising a mattress and a mattress foundation.
Foundations, such as box springs, are generally required to have
fire-blocking on the borders or sides. The foundation top panel is
normally in contact with the mattress and is somewhat shielded from
flame so the material used in the foundation panel does not
typically have to have the same degree of fire-blocking as say, the
panel of the mattress. While not meant to be limiting, FIGS. 6 and
7 show a very simplified illustration of a type of foundation, a
box spring, with two common types of fire-blocking arrangements.
Referring to FIG. 6, box spring foundation 30 is covered on the top
panel and all borders with fabric composite 31. Under the fabric,
composite is a layer of support foam 32. The support foam is
attached to a support structure 33 that is normally made from wood
or some other rigid material. In some cases there is a large open,
area 34 in the foundation that is covered on the bottom by a thin
nonwoven fabric dust cover 35. An alternative arrangement is
illustrated in FIG. 7. Mattress foundation 40 is covered on the top
panel with an alternative top fabric 41 that is different from the
fabric composite 31. This top fabric panel covers the top face
while the fire-blocking is provided for all four borders to prevent
the intrusion of the flame jet during the flammability testing.
Because the top panel of the foundation is covered by the mattress,
the top fabric panel need not be as flame retardant as the borders
of the foundation. Further, the mattress foundation may not have a
large degree of cushioning material in the border and/or the panel.
It is sufficient to have a single layer fire-blocking fabric
underneath the outer ticking in the mattress foundation border.
[0044] Mattress sets of this invention have a peak heat release of
less than 150 kilowatts within the first 30 minutes of the test,
and preferably within the first 60 minutes of the test, when tested
according to this Technical Bulletin. Additionally, mattresses of
this invention may have a total heat release of less than 25
megajoules within 10 minutes when tested according to this
technical bulletin.
Process for Fire-Blocking Mattress
[0045] This invention is further directed to a process for
fire-blocking a mattress by incorporating into the mattress a
fire-blocking fabric between the cushioning material and the
mattress core, the fire-blocking fabric being a single layer of
nonwoven fabric comprising at least 0.5 ounces per square yard (17
grams per square meter) of a cellulose fiber that retains at least
10 percent of its fiber weight when heated in air to 700 C at a
rate of 20 degrees C. per minute and at least 0.5 ounces per square
yard (17 grams per square meter) of a heat-resistant fiber.
[0046] The fire-blocking fabric can be preferably incorporated into
the mattress by first combining, in order, ticking fabric,
cushioning material, and fire-blocking fabric into a fabric
composite. The layers of the fabric composite can be stitched
together and then the fabric composite can be used to cover the
mattress core. The fabric composite can be attached to the mattress
core by an appropriate means such as stitching. An alternate method
of incorporating the fire-blocking fabric into the mattress is by
placing individual layers of fire-blocking fabric, cushioning
material, and ticking fabric on the mattress core and stitching the
layers to the mattress core.
Test Methods
Mattress Burn Performance
[0047] The Bureau of Home Furnishings and Thermal Insulation of the
Department of Consumer Affairs of the State of California (3485
Orange Grove Avenue, North Highlands, Calif. 95660-5595, USA)
published Technical Bulletin 603 "Requirements and Test Procedure
for Resistance of a Residential Mattress/Box Spring Set to a Large
Open-Flame" dated February 2003 to quantify the flammability
performance of mattress sets. This protocol provides a means of
determining the burning behavior of mattress/foundation sets by
measuring specific fire test responses when the mattress plus
foundation are exposed to a specified flaming ignition source under
well-ventilated conditions. It is based on the National Institute
of Standards and Technology Publication titled "Protocol of Testing
Mattress/Foundation Sets Using a Pair of Gas Burners" dated
February 2003.
[0048] Test data are obtained that describe the burning during and
subsequent to the application of a specific pair of gas burners
from the point of ignition until (1) all burning of the sleep set
has stopped, (2) a period of one hour has elapsed, or (3) flashover
of the test room appears inevitable. The rate of heat release from
the burning test specimen (the energy generated by the fire) is
measured by oxygen consumption calorimetry. A discussion of the
principles, limitations, and requisite instrumentation are found in
ASTM E 1590 "Standard Test Method of Fire Testing of Mattresses".
Terminology associated with the testing is defined in ASTM E 176
"Standard Terminology of Fire Standards".
[0049] In general, the test protocal utilizes a pair of propane
burners, designed to mimic the heat flux levels and durations
imposed on a mattress and foundation by burning bedclothes. The
burners impose differing fluxes for differing times on the mattress
top and the side of the mattress/foundation. During and subsequent
to this exposure, measurements are made of the time-dependent heat
release rate from the test specimen.
[0050] The mattress/foundation is placed on top of a short bed
frame that sits on a catch surface. During the testing, the smoke
plume is caught by a hood that is instrumented to measure heat
release rate. For practicality, twin-sized mattresses and
foundations are tested. After ignition by the burners, the specimen
is allowed to burn freely under well-ventilated conditions.
[0051] A representative illustration of the general locations of
the gas burners, not drawn to scale, is shown in FIG. 8. Test
specimen 50 includes a mattress 51 is placed on foundation 52 with
T-shaped burners 53 and 54 set to burn the specimen. Burner 53
impinges flames on the top surface of the mattress and is set 39 mm
from the surface of the mattress. The second burner 54 impinges
flames vertically on the side of the mattress/foundation
combination and is set 42 mm from the side of the specimen. The
side burner and the top burner are not set at the same place along
the length of the specimen but are offset from on another along the
length approximately 18 to 20 cm as generally illustrated in FIG.
9. The burners are specially constructed and aligned per the test
method.
[0052] The test specimen is conditioned for 24 hours prior to the
testing at an ambient temperature of above 12 Celsius (54
Fahrenheit) and a relative humidity of less than 70 percent. The
test specimen of mattress and foundation is centered on each other
and the frame and catch surface. If the mattress is 1 to 2 cm
narrower than the foundation the mattress may be shifted until the
sides of the mattress and foundation are aligned vertically. The
burners are aligned and spaced from the specimen per the standard.
Data recording and logging devices are turned on at least one
minute prior to ignition. The burners are ignited and the top
burner is allowed to burn for 70 seconds while the side burner is
allowed to burn for 50 seconds (if possible) and then they are
removed from the area. Data collection continues until all signs of
burning and smoldering have ceased or until one hour has
elapsed.
ThermoGravametric Analysis
[0053] The fibers used in this invention retain a portion of their
fiber weight when heated to high temperature at a specific heating
rate. This fiber weight was measured using a Model 2950
Thermogravimetric Analyzer (TGA) available from TA Instruments (a
division of Waters Corporation) of Newark, Del. The TGA gives a
scan of sample weight loss versus increasing temperature. Using the
TA Universal Analysis program, percent weight loss can be measured
at any recorded temperature. The program profile consists of
equilibrating the sample at 50 degrees C.; ramping the temperature
at from 10 or 20 degrees C. per minute from 50 to 1000 degrees C.;
using air as the gas, supplied at 10 ml/minute; and using a 500
microliter ceramic cup (PN 952018.910) sample container.
[0054] The testing procedure is as follows. The TGA was programmed
using the TGA screen on the TA Systems 2900 Controller. The sample
ID was entered and the planned temperature ramp program of 20
degrees per minute selected. The empty sample cup was tared using
the tare function of the instrument. The fiber sample was cut into
approximately 1/16''0 (0.16 cm) lengths and the sample pan was
loosely filled with the sample. The sample weight should be in the
range of 10 to 50 mg. The TGA has a balance, therefore the exact
weight does not have to be determined beforehand. None of the
sample should be outside the pan. The filled sample pan was loaded
onto the balance wire making sure the thermocouple is close to the
top edge of the pan but not touching it. The furnace is raised over
the pan and the TGA is started. Once the program is complete, the
TGA will automatically lower the furnace, remove the sample pan,
and go into a cool down mode. The TA Systems 2900 Universal
Analysis program is then used to analyze and produce the TGA scan
for percent weight loss over the range of temperatures.
EXAMPLE 1
[0055] Three sleep sets, each comprised of a mattress and
foundation, were made using typical mattress and box spring
construction techniques, each set only differing in the type and
basis weight of fire-blocking fabric used. The mattress core was a
standard steel coil construction covered with a fiber pad and a 0.5
inch (1.25 centimeter) foam sheet. The foundation was a standard
steel coil and wood box construction. All mattresses were a tight
(smooth) top style. Table 1 lists the composition and basis weight
of the fire-blocking fabric used in the five mattresses.
TABLE-US-00002 TABLE 1 PHRR < PHRR < THR < Item Basis
weight, 150 kw 150 kw 25 MJ No. Composition oz/yd.sup.2 (g/m.sup.2)
30 min 60 min 10 min 1 50% Kevlar .RTM./ 2.5 (85) Pass Pass Pass
50% Visil .RTM. 2 33% Kevlar .RTM./ 3.0 (102) Pass Fail Pass 67%
Visil .RTM. 3 25% Kevlar .RTM./ 4.0 (136) Pass Pass Pass 75% Visil
.RTM. PHRR--Peak Heat Release Rate THR--Total Heat Release
[0056] Panel material for the mattresses was assembled by quilting
together with standard polyester thread the following components in
the order: 3.5 oz/yd.sup.2 woven polyester ticking fabric,
approximately 0.75'' polyester batting having an areal density of
0.75 oz/yd.sup.2, a single layer fire-blocking fabric from Table 2,
1'' polyurethane foam sheet, 0.5'' polyurethane foam sheet, and a
nonwoven backing sheet of approximately 1 oz/yd.sup.2. The panel
material was used to cover both sides (top and bottom) of the
two-sided mattresses.
[0057] Border material was assembled in a separate operation by
quilting together with standard polyester thread the following
components in the order: 3.5 oz/yd.sup.2 woven polyester ticking
fabric, approximately 0.375'' polyurethane foam having an areal
density of 2.5 oz/yd.sup.2, the same fire-blocking fabric selected
from Table 2 (same as used for the panel). The border material was
used to cover all four vertical sides of the mattresses.
[0058] The border material was also used on the four vertical sides
of the foundation employing a 2 inch (5.1 centimeter) continental
or waterfall design on the upper edge of the foundation, a design
in which the border material is folded over the upper edge and
extends onto the foundation top panel.
[0059] The foundation top panel area within the continental edge
was covered with a 4 oz/yd.sup.2 (136 g/m.sup.2) of spunlaced
nonwoven fabric (having a composition of 25% Kevlar.RTM. and 75%
Visil.RTM.) under a standard non-skid pad. All border and panel
composite material seams were sewed with a thread containing
Kevlar.RTM. fiber. FR-treated polyester seam tape was also used
throughout.
[0060] The three sleep sets were individually burned according to
Technical Bulletin 603 of the State of California. Burn results are
summarized in Table 2. All had a Peak Heat Release Rate of less
than 150 kilowatts in the first 30 minutes with a Total Heat
Release of less than 25 megajoules in the first 10 minutes. Two of
the mattresses also had a Peak Heat Release Rate of less than 150
kilowatts in the first 60 minutes.
EXAMPLE 2
[0061] Two sleep sets, each comprised of a mattress and foundation,
were made using the same techniques and materials as Example 1;
however, a) the nonwoven fire-blocking fabric used in the mattress
top panel and borders contained an off-gassing material that
released a flame suppressing gas when burned and b) this nonwoven
fire-blocking fabric was a single-layer needlepunched felt nonwoven
fabric. The compositions and basis weights of these top panel
fabrics are shown in Table 3. The bottom panels of the mattresses
were made from the same material as the top panel of the
foundation, that is the bottom panel was covered with a 4
oz/yd.sup.2 (136 g/m.sup.2) of spunlaced nonwoven fabric (having a
composition of 25% Kevlar.RTM. and 75% Visil.RTM.) under a standard
non-skid pad.
[0062] Both sleep sets were burned as in Example 1 and both passed
the Peak Heat Release Rate tests at both 30 and 60 minutes and the
Total Heat Release test in the first 10 minutes. TABLE-US-00003
TABLE 2 PHRR < PHRR < THR < Item Basis weight, 150 kw 150
kw 25 MJ No. Composition oz/yd.sup.2 (g/m.sup.2) 30 min 60 min 10
min 1 20% Kevlar .RTM./ 6.5 (220) Pass Pass Pass 40% Visil .RTM./
40% Modacrylic 2 20% Kevlar .RTM./ 6.5 (220) Pass Pass Pass 40%
Visil .RTM./ 40% Polyvinyl Chloride PHRR--Peak Heat Release Rate
THR--Total Heat Release
* * * * *