U.S. patent application number 12/619284 was filed with the patent office on 2010-06-17 for fire and sag resistant acoustical panel and substantially clear coating therefor.
Invention is credited to Michelle X. Wang, Anthony L. Wiker.
Application Number | 20100146887 12/619284 |
Document ID | / |
Family ID | 42170225 |
Filed Date | 2010-06-17 |
United States Patent
Application |
20100146887 |
Kind Code |
A1 |
Wiker; Anthony L. ; et
al. |
June 17, 2010 |
Fire and Sag Resistant Acoustical Panel and Substantially Clear
Coating Therefor
Abstract
A ceiling panel structure which includes a fire retardant mat, a
scrim and a substantially clear scrim coating. The fire retardant
mat includes a fire retardant fiber component and a binder material
which binds the fibers. The fire retardant fiber component includes
natural fibers treated with a fire retardant. The scrim being
attached to a surface of the mat and the substantially clear
coating is applied to the surface of the scrim opposite a surface
of the scrim positioned next to the mat. The ceiling panel
structure has flame spread index of 25 or less and a smoke
generation index of 50 or less, as measured by ASTM E 84 that is
uniform throughout the mat.
Inventors: |
Wiker; Anthony L.;
(Lancaster, PA) ; Wang; Michelle X.; (Lititz,
PA) |
Correspondence
Address: |
ARMSTRONG WORLD INDUSTRIES, INC.;LEGAL DEPARTMENT
P. O. BOX 3001
LANCASTER
PA
17604-3001
US
|
Family ID: |
42170225 |
Appl. No.: |
12/619284 |
Filed: |
November 16, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61114778 |
Nov 14, 2008 |
|
|
|
Current U.S.
Class: |
52/232 ;
52/783.1 |
Current CPC
Class: |
Y10T 428/249921
20150401; D21H 21/34 20130101; Y10T 442/198 20150401; D21H 13/40
20130101; E04B 9/001 20130101; D21H 17/66 20130101; E04B 9/045
20130101 |
Class at
Publication: |
52/232 ;
52/783.1 |
International
Class: |
E04B 1/94 20060101
E04B001/94; E04C 2/26 20060101 E04C002/26 |
Claims
1. A ceiling tile structure comprising: a fire retardant mat and a
scrim attached to a surface thereof, wherein the fire retardant mat
comprises a binder and a fiber component, the fiber component
including natural fibers treated with a fire retardant material;
and a substantially clear coating on a surface of the scrim
opposite a surface of the scrim positioned next to the fire
retardant mat, the coating comprising a fire retardant, a binder, a
clay, a dispersant, and a defoamer; wherein the fire retardant mat
having a fire rating that is uniform throughout all planes of the
fire retardant mat, and wherein the fire rating includes a flame
spread index value of 25 or less and a smoke generation index value
of 50 or less, as measured by ASTM E 84.
2. The ceiling tile structure of claim 1, comprising a coating on a
surface of the fire retardant mat opposite the scrim.
3. The ceiling tile structure of claim 1, wherein the flame spread
index value is 10 or less and the smoke generation index value is
10 or less, as measured by ASTM E 84.
4. The ceiling tile structure of claim 1, wherein the fire
retardant material is di-ammonium sulfate.
5. The ceiling tile structure of claim 4, wherein the flame spread
index value is 10 or less and the smoke generation index value is
10 or less, as measured by ASTM E 84.
6. The ceiling tile structure of claim 1, wherein the density of
the fire retardant mat in the range from about 4 to about 8
lb/ft3.
7. The ceiling tile structure of claim 1, wherein the thickness of
the fire retardant mat in the range from about 0.25 to about 2
inches.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit under 35 U.S.C.
.sctn.119(e) of U.S. provisional application Ser. No. 61/114,778,
filed Nov. 14, 2008, entitled "Fire Retardant Mat And Ceiling Tile
Structure Incorporating The Same."
BACKGROUND OF THE INVENTION
[0002] The present invention is directed to fire and sag resistant
panel, and, more particularly, to an enhanced fire rated, sag
resistant acoustical ceiling panel having an enhanced fire rated
natural fiber mat incorporated therein as well as a substantially
clear coating applied thereto.
[0003] Natural fibers such as hemp, kenaf, jute, sisal and flax,
are gaining interest as a component in a variety of manufactured
products, including products for the interior building environment,
as natural fibers are a renewable resource and do not emit
potentially hazardous materials into the environment. Though
renewable and environmentally friendly, natural fibers, and the
binder material which holds the fibers together, are highly
flammable.
[0004] Articles intended for use specifically in a construction
which is utilized as a conduit for return air must achieve an
exceptional Class A fire resistance rating: namely a flame spread
index value of 25 or less and a smoke generation index value of 50
or less, as measured by ASTM E 84. Additionally, when an article is
suspended horizontally in a room space, such as in an acoustical
ceiling system, not only must the efficacy of any flame retardant
applied to natural fibers be substantial but it is also desired
that these panels be: highly acoustically permeable; dimensionally
stable; self-supporting; and sag resistant with respect to
fluctuations in relative humidity. As one of ordinary skill in the
art would understand, increasing the amount of binder to improve
such features as the self-supporting nature of the fibrous mass, in
turn, makes the fibrous article more flammable. As a result of such
inverse relationships, an article possessing a combination of the
aforementioned properties has not been heretofore achieved.
SUMMARY OF THE INVENTION
[0005] The invention is a ceiling panel structure which includes a
fire retardant mat. The fire retardant mat includes a fire
retardant fiber component and a binder material which binds the
fibers. The fire retardant fiber component includes natural fibers
treated with a fire retardant. The fire retardant mat has flame
spread index of 25 or less and a smoke generation index of 50 or
less, as measured by ASTM E 84 that is uniform throughout the mat.
The ceiling panel structure also includes a scrim attached to the
bottom surface of the fire retardant mat as well as a substantially
clear coating on the exposed surface of the scrim opposite the fire
retardant mat. The ceiling panel structure also achieves a flame
spread index value of 25 or less and a smoke generation index value
of 50 or less, as measured by ASTM E 84 that is uniform throughout
the structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a side view of a fire retardant mat according to
an embodiment of the invention.
[0007] FIG. 2 is a side view of a ceiling panel structure
incorporating the fire retardant mat of FIG. 1.
DETAILED DESCRIPTION OF THE EMBODIMENT(S)
[0008] FIG. 1 shows a fire retardant mat 1 according to an
embodiment of the invention. In order to form the fire retardant
mat 1, a fiber component comprising natural fibers treated with the
fire retardant is mixed with a binder to form a blend. The fiber
component may be mixed with the binder, for example, by carding and
co-mingling the fiber component with the binder in an air stream,
which separates the natural fibers from one another and intimately
blends the natural fibers with the binder. The blend, or furnish,
is then deposited onto a foraminous wire and is compressed to a
desired final thickness. Heat is then applied through the fiber web
to either melt a thermoplastic binder or cure a thermosetting
binder. Alternatively, the blend may be conveyed through an oven
that blows heat through the mixture while the mixture is
simultaneously being compressed with one or more wire screens.
[0009] As previously mentioned, the fiber component includes
natural fibers treated with a fire retardant. Bast fibers such as
kenaf, hemp, flax, ramie, or jute are examples of natural fibers.
The natural fiber ingredient may comprise a single type of fiber or
a combination thereof. Additionally, a portion or all of the
natural fibers may be recycled fibers. Kenaf, jute, hemp, or
combinations thereof are preferred where strength and/or rigidity
is sought as these particular fibers are inherently less flexible
than other natural fibers.
[0010] The fire retardant may be in the form of a powder or liquid
and can be, for example, ammonium phosphates, sodium pentaborates,
ammonium sulfates, boric acids and mixtures thereof. The fiber
component comprises from about 70-99% by dry weight of the mat, and
more preferably from about 70 to about 83% by dry weight of the
mat. The ratio of the natural fiber to fire retardant in the fiber
component is in the range from about 4:1 to about 11.5:1 and more
preferably about 5:1.
[0011] The amount of binder in the mat in the mat is in the range
from about 1 to about 30% by dry weight of the fiber mat. The
binder can be either thermoplastic (including bio-based polymers)
or thermosetting. For a thermoplastic binder, the material range is
more preferably from about 11 to about 30%; most preferably about
13 to about 21%. For a thermosetting binder, the material range is
more preferably from about 1 to about 15%; most preferably about 2
to about 8%.
[0012] It is well understood in the art that the softening or
curing temperature be below the temperature that would cause
undesired thermal degradation of the natural fibers. A well known
thermoplastic binder fiber is the bi-component sheath-core
configuration having a first thermoplastic material coated or
encased within a second thermoplastic material having a lower
softening temperature. The first thermoplastic material may be, for
example, polyethylene terephthalate glycol (PETG), and the second
thermoplastic material may be, for example, polyethylene
terephthalate (PET).
[0013] In the following examples, jute fiber was treated either
with a system of ammonium phosphate and borate or with di-ammonium
sulfate. The results according to ASTM E 84 for measuring the flame
spread and smoke generation index values are shown in Tables 1 and
2. It should be noted that the preferred mat density for use in a
ceiling tile structure is in the range from about 4 to about 8
lb/ft.sup.3 and, more preferably from about 5 to about 6.5
lb/ft.sup.3; most preferably about 5.5 lb/ft.sup.3. The preferred
thickness of the mat for use in a ceiling tile structure is in the
range from about 0.25 to about 2 inches, more preferably about
0.0.375 to about 1.5 inches and most preferably from about 0.4 to
about 0.7 inches.
TABLE-US-00001 TABLE 1 % of fibrous Basis Flame- Smoke component
Binder Weight Mat Mat spread Generation that is FR Binder Amount of
Mat Thickness Density Index Index Mat FR (dry wt %) Type (dry wt %)
(g/m2) (in) (lb/ft3) Value Value 1 Ammonium 15 110 C. 15 1127 0.42
6.6 25 2 Phosphate/ Low- Borate melt Bico 2 Ammonium 15 110 C. 18.5
923 0.528 4.3 32 9 Phosphate/ Low- Borate melt Bico 3 Ammonium 15
110 C. 20 1145 0.512 5.5 34 7 Phosphate/ Low- Borate melt Bico
TABLE-US-00002 TABLE 2 % of fibrous component Binder Basis Flame-
that is Amount Weight Mat Mat spread Smoke FR (dry wt Binder (dry
wt of Mat Thickness Density Index Generation Mat FR %) Type %)
(g/m2) (in) (lb/ft3) Value Index Value 4 Diammonium 15.6 110 C. 13%
1472 0.62 5.8 10 5-10 Sulfate Low- melt Bico 5 Diammonium 15.6 110
C. 15% 1422 0.67 5.2 10 5-10 Sulfate Low- melt Bico 6 Diammonium
15.6 110 C. 17% 1513 0.66 5.64 10 10 Sulfate Low- melt Bico 7
Diammonium 15.6 110 C. 19% 1571 0.64 6.03 10 10 Sulfate Low- melt
Bico 8 Diammonium 15.6 110 C. 21% 1596 0.64 6.12 10 10 Sulfate Low-
melt Bico
As shown in Table 1, only sample 1 having a binder level of 15% by
wt. of the mat achieved the exceptional Class A fire rating sought
when using the system of ammonium phosphate and borate, i.e. a
flame spread index reached the 25 value threshold. In contrast when
18.5% bonder or greater was utilized, the flame spread index value
was too high. The use of di-ammonium sulfate achieved the
exceptional Class A rating both at lower and higher binder levels.
Moreover, flame spread index value reached 10 and the smoke
generation index value reached 5 when the di-ammonium sulfate was
used.
[0014] It should be noted that this exceptional Class A fire rating
for each of the examples is uniform throughout the entire fire
retardant mat 1. What is meant by "uniform throughout the entire
fire retardant mat" is that any cross-sectional surface of the fire
retardant mat 1 has the same fire rating as any outside surface of
the fire retardant mat 1.
[0015] A facing scrim 3 and a scrim coating 6 composite was then
adhered to sample mats 4-8 of Table 2. The scrim applied to sample
mats 4-8 was a fiberglass scrim available from Owens Corning, item
number A80PKR-YK111, however, the scrim 3 may be any suitable scrim
that is resistant to flame spread and preferably has a Class A fire
rating of 25/50, examples of which are fiberglass or flame
retardant blends of fiberglass, cellulose and polyester. The
fiberglass scrim is bound with a flame retarded polymeric binder.
The scrim 3 can be attached to a surface of the fire retardant mat
1 using any suitable attachment method. Here, the fiberglass scrim
is affixed to the mat with flame-retarded vinyl-acetate glue 5. The
air flow resistance of the A80PKR-YK111 scrim is 40 MKS Rayls.
[0016] In the example embodiments set forth above, the scrim was
then painted with DURABRITE paint available from Armstrong World
Industries. The paint was applied at an application level of 29
g/ft2. What is key for achieving the desired acoustic performance
in the fully constructed ceiling panel is that the combination of
the scrim, the glue application and the paint application must have
an air-flow permeability that allows sound to enter and be absorbed
in the structure. A composite air flow resistance of about 400 to
about 600 MKS Rayls has been found to achieve an noise reduction
coefficient (NRC) greater than 0.80. In order to achieve the
desired air flow resistance, and thus, the desired NRC, the scrim
weight must be in the range from about 4.5 to about 10.5 g/ft2 and
the glue application rate must be in the range from about 3 to
about 10 g/ft2 (dry weight). The paint application rate must be in
the range from about 10 to about 50 g/ft2 (dry weight).
[0017] Table 3 illustrates examples of fully constructed two feet
by two feet panels comprising the fire retardant mat samples shown
in Table 2.
TABLE-US-00003 TABLE 3 Binder Flame- Amount Sag spread Smoke in mat
NRC of Performance Index of Index of Sample (dry wt Panel of Panel
Panel Panel Mat %) Structure Structure Structure Structure 4 13%
0.85-0.90 -162, -224 0 0 5 15% 0.85-0.90 -150 10 5 6 17% 0.85 -128
10/5 5/0 7 19% N.D. N.D. 8 21% N.D. N.D.
[0018] The completed structural panels utilizing sample mates 4-8
were indeed found to obtain the desired fire resistance, sag and
acoustical properties. Specifically, a completed structural panel
achieved a noise reduction coefficient (NRC) of at least 0.85. The
noise reduction coefficient (NRC) is a useful indicator of the
acoustical properties of a given material. The Noise Reduction
Coefficient (NRC) is a scalar representation of the amount of sound
energy absorbed upon striking a particular surface. It is well
known in the art that NRC is the average of four sound absorption
coefficients of the particular surface at frequencies of 250 Hz,
500 Hz, 1000 Hz, and 2000 Hz.
[0019] In addition, the desired sag performance was also achieved;
namely a statistical value more positive than negative 0.150
inches. To measure the sag performance, several 2.times.2 inch
panels were suspended horizontally from a perimeter support frame
and deflection was measured over the course of four 24-hour cycles
in which relative humidity was varied: namely 8 hours at 90%
relative humidity and then 6 hours at 35% relative humidity. The
negative most deflection from horizontal was recorded for each
panel formulation. Statistically, an average negative value minus 2
standard deviations that is more negative than negative 0.150
inches represents a threshold performance value for a 2.times.2
panel at which the sag in the middle of the panel becomes apparent
and begins to show an unsightly pillowed appearance in a horizontal
installation.
[0020] The foregoing illustrates some of the possibilities for
practicing the invention. Many other embodiments are possible
within the scope and spirit of the invention. For example, although
the fire retardant mat 1 is shown and described herein as being
incorporated in the ceiling tile structure 2, it will be
appreciated by those skilled in the art, however, that the fire
retardant mat 1 may have other applications, for example, in the
building, furniture, or automotive industry. It is, therefore,
intended that the foregoing description be regarded as illustrative
rather than limiting, and that the scope of the invention is given
by the appended claims together with their full range of
equivalents.
[0021] For example, the coating 6 may be colored, opaque, or
substantially clear depending on the desired appearance of the
ceiling tile structure 2. For example, suitable substantially clear
coatings include Safe-T-Guard, WT-103, No. 133A, Flamex PF, JB-1D,
Fabric Seal concentrate, Flamort 6-3, Disflammoll DPO, and DPK. A
substantially clear coating may comprise, for example, a fire
retardant, a binder, a clay, a dispersant, and a defoamer. The fire
retardant may be halogen free and may comprise at least one
material selected from the group consisting, for example, of
ammonium polyphosphate (Exolit AP 420, 412, 422, and 423) and
melamine polyphosphate (Flamestab Nor 116, Melapur MC 15, MP, and
200). The binder may be selected to prevent yellowing, offer
moisture resistance, and provide durability. The binder may be, for
example, an acrylic binder. Suitable binders include, for example,
vinyl acrylic Rovace 9100, Flexbond 325, acrylic Rhoplex AC 260,
ethylene vinyl chloride Airflex 4530, and polyvinyl acetate Vinac
828 m. The fire retardant dosage is in the range from about 5%- to
about 95% by weight and the binder level is in the range from about
3% to about 95% by weight. The solids of the substantially clear
coating are in the range from about 30% to about 60% by weight; the
application rate is in the range from about 8 to about 42 g/ft2 and
the filler/binder ratio is about 0.05:1 to about 33:1.
[0022] The substantially clear coating according to one embodiment
of the invention comprises about 85 to about 87% by weight ammonium
polyphosphate (e.g. Exolit AP 423), about 4 to about 7% by weight
clay (e.g. EG 44), about 6 to about 8% by weight acrylic binder
(e.g. Rhoplex AC 261), about 0.1 to about 0.4% by weight dispersant
(e.g. Nopcote 63900), and about 0.01 to about 0.05% by weight
defoamer (e.g. Tego Foamex 1488). The solids of the substantially
clear coating are about 35-42% weight with Brookfield viscosity
approximately 300-500 cps at 10 rpm with a #1 spindle. The
filler/binder ratio is about 10:1 and about 14:1 and the
application rate is about 6-32 grams per feet squared.
[0023] Moreover, such substantially clear coating shown and
described herein is fire retardant and is substantially durable and
moisture resistant such that the coating 6 adequately protects the
scrim 3 and provides RH 70 & RH 90 sag resistance for the fire
retardant mat 1 when the scrim 3 is attached thereto. Additionally,
because the coating 6 is substantially clear, the natural fiber
elements of the scrim 3 are visible, which causes the ceiling tile
structure 2 to have an aesthetically pleasing and natural look.
Further, the coating 6 is environmentally friendly in that it does
not contain formaldehyde, acetaldehyde, or halogen.
[0024] Yet another modification is that a second coating 4 may be
applied to the surface of the fire retardant mat 1 opposite the
scrim 3 to help provide rigidity and stability against sag induced
by fluctuations in relative humidity. This coating must have a low
surface flame-spread smoke generation and allows the product to
meet the Class A 25/50 requirement. In one example embodiment, the
back coating 4 may be a filled styrene acrylate latex resin which
is a non-cross linking thermoplastic resin of substantially high
T(g). The T(g) of the latex is important with respect to sag and
should be in the range of about 0.degree. C. to about 100.degree.
C. For a filled styrene acrylate latex resin the T(g) is 33.degree.
C. The application weight of the back coat is in the range from
about 20 to about 70 g/ft2 dry wt. and preferably about 45 g/ft2
dry wt. A filler/binder ratio range for the back-coat would be in
the range from about 30:1 to about 5:1, and preferably 20:1.
[0025] The back-coat can optionally be formulated with a reactive
thermosetting or hydrogen bonding binder. Examples of thermosetting
binders are: acrylic, (i.e. our Armstrong ESP back-coat),
phenol-formaldehyde, melamine or urea formaldehyde, epoxy,
polyurethane, or poly-urea. Examples of hydrogen bonding binders
are polyvinyl alcohol and starch, or other polysaccharide or polyol
binders. Effective filler/binder ratio and back-coat application
weight ranges would be from about 10/1 t about 1/1 and from about 5
to about 30 g/ft2, respectively.
[0026] Alternatively, instead of a coating, the back-side could
have a fiberglass or other stable scrim adhered thereto. The scrim
may or may not need to be painted on its opposite face depending on
the ability of such a scrim to resist flame-spread and smoke
generation to the point that the product meets Class A 25/50
performance. If necessary, an inert paint could be applied to the
scrim at a low level to reduce surface flame-spread without
impacting the products acoustical performance.
* * * * *