Note: Descriptions are shown in the official language in which they were submitted.
~t~ 3
08CT04963
FIBER REINFORCED THERMOPLASTI~ COMPpSI~ES
AS FIRE/HEAT BARRIERS _QB ÇOMBUSTIBLE SUBSTRATES
Walter L. Hall
Erich O. Teu~sch
BACKGRO~ND QF THE INVENTIO~
Field of the_Invention
The present invention relates to fire resistant
structures, and more particularly r~lates to
multilayered structures having a fiber reinforced
protective layer and a protected substrate layer.
De~i pti on of Re~ a~ed Art
5Structural materials such as sheets of wood,
plywood, particle board, and oriented strand board
find wide spread use in the building industry. Each
of these materials, while providing desired levels
of strength and economy, have, however, generally
lo exhibited undesirably low levels of heat and fire
resistance.
Accordingly, one object of the present
invention is to provide wooden structures which
exhibit desired levels of heat and fire resistance.
SUMMARY OF THE INVENTION
15The present invention provides a fire resistant
structure having a compressed fiber reinforced
composite layer and a wooden substrate.
DETAILED DESCRIPTION OF THE INVENTION
The fire resistant structures of the present
invention have a compressed, fire resistant
20composi te 1 ayer and a protected wooden substrate
layer.
The fire resistant composite layer has
respective amounts of (i) fire resist~nt fibers and
~ii) a binder material.
25The fi re resi stant fi bers are preferably in the
form of single discrete fibers and preferably have a
2 ~ ~, 3 ~3 ~ j 08i::T04963
high modulus of elas~ici~y. The fire resistant
fibers preferably neither melt nor lose their high
modulus of elastici~y at temperatures below 400~C,
and more preferably 600C. Suitable fibers include
glass, carbon, mineral and ceramic fibers and
certain polymeric fibers such as aramid ~ibers sold
under the trade names Kevlar and Nomex. Preferably,
the fibers have a modulus of elasticity hiyher than
10,000 Mega Pascals.
lo Suitable fibers have at least 50% by weight
fiber strands having a length between about 0.125
inch and about 1.0 inch, more preferably between
0.125 and 0.5 inch, and most preferably about 0.5
inch. The fibers preferably have an average
diameter of from between 2 microns and 30 microns,
more preferably between 12 microns and 23 microns
and most preferably about 16 microns. Fiber length
is important in providing the desired level of
lofting in structure upon exposure to heat. Fibers
which are either too long or too short provide
inadequate levels of lofting. Fiber diameters are
important in providing the desired levels vf fiber
stiffness~ Fibers which are too thin lack the
desired levels of stiffn~ss for lofting and fibers
which are too thick are also generally ~oo stiff and
break during compression.
The birder material is prefer2bly an organic
material and may be selected from resins including
both thermoplastics and thermosets. The binder
30 material upon consolid~tion forms a solid matrix
~hich serves to bond the fibers toge~her in the
composi te 1 ayer. The bi nder preferably is a
thermoplastic material.
Suitable thermoplastic materials for forming a
binder matrix inolude polyolefins, polyesters,
6~3) ~,3' r~
OaCT~ 49 63
-- 3
polyamides, polyethers, polycarbonates,
acrylonitrile styrene-butadiene copolymer,
polyvinylchloride, and polystyrenes.
Sui tabl e pol yol e~i ns include a polymerization
5 produc~ of at least one aliphatic ethyleneically
unsaturated monomer and is selected from
polyethylene and other ~olyolefins and copolymers of
such monomers, for example, polyethylene,
polybutene, polypropyl ene, polypentene,
poly~methylpentene~, normally solid copolymer of
ethyl ene and butene-1, copolymers of ethylene and
ethyl acrylate, or vinyl acetate,
butadiene-acrylonitrile copolymers, ionomers,
poly(methyl methacrylate), polyisobutylene rubbers
and the like, poly(vinyl chloride), poly(vinylidene
chloride), a copolymer of vinyl chloride with vinyl
acetate, natural rubber, a rubbery copolymer of
butene-1 and ~thylene, a rubbery copolymer of
butadiene and acrylonitrile, and the like. All such
polymers are commercially available or can be
prepared by techniques well known to those skilled
in the art. As ~o ~he copolymers and terpolymers,
the proportions of the repeating units may vary
broadly and will be selected to provide the desired
characteristics, i.e., normally ru~bery, normally
solid, and the like. In addition to the polymers
illustrated above, other suitable polymerization
products of aliphatic ethyleneically ~nsaturated
monomers include derivatives thereof, sueh as
3Q halogenated hydrocarbon polymers, e.g., chlorin~ted
polyethylene, chlorssulfonated polyhydrocarbons and
polymerized carboxy-substituted butadiene and the
like.
Other preferred thermoplastics are selected
from polyacetal homopolymers, such as
~r~i .? ~
osc~o~s63
polyoxymethylene, polyacetal copolymers, such as
those based on trioxane, polyphenylene ethers, such
as poly(2,6-dimethyl-1,4-phenylene)ether,
polysulfones, such as the condensation product of
bisphenol A and 4,4'-dichlorodiphenyl sulfone,
polyamides, such as polycaprolactam, or the product
of hexamethylenediamine and adipic acid, polyimides,
e.g., the product of bismaleimido diphenyl methane
and methylene dianiline, normally solid or normally
lo rubbery polyorganosiloxanes, such as polyalkyl or
aryl-siloxanes, or combinations of the two, and
copolymers of polyorganosiloxanes with vinyl
aromatics, e.g., styrene, acrylic monomers, e.g.,
methyl methacrylate, or aromatic esters, e.g., ~he
15 reaction products of bisphenol A and iso or
terephthaloyl chloride, as well as siloxane-nitrogen
copolymers containing amido, amide-imido and imide
groups. All such polymers are either commercially
available or can be made in ways known to those
skilled in the art.
Also preferred are ~hermoplastics which
comprise mixtures of any of the above-mentioned
thermoplastics. For example, one such mixture would
comprise a high molecular weight composition which
is a combination of polystyrene or other styrene
resin, including rubber modified polystyrenes (i )
with a condensation product of 2,6-dimethylphenol,
i.e., poly(2,6-dimethyl-1,4-phenylene)ether.
Typi cal of the polyester resi ns sui tabl e for
30 this invention are poly(alkylene terephthalates,
i sophthal ates or mi xed terephthal ~tes and
i sophthal ates ), wherei n the al kyl ene groups contai n
from 2 to 10 carbon atoms. They are avai 1 abl e
commercially or can be prepared by known techniques,
35 such as by the alcoholysis of esters of the phthalic
~ ~ 3 ,~
08CT04963
acid with a glycol and subsequent polymerization, by
heating glycols with the free acids or with halide
derivatives thereof, and similar processes. These
are described in U.S. Patent No. 2,465,319 and
3,047,539 and elsewhere.
Although the glycol portion of such typical
polyesters can contain from 2 to 10 carbon atoms,
e.g.p 1,2 ethylene, 1,3-propylene, 1,4-butylene,
1,3-butylene, 1,2-propylPne, 1,2-butylene,
2,3-butylene, 1,6-hexylene, 1,10-decylene, etc., it
is preferred that it contain 2 or 4 carbon atoms, in
the form of linear methylene chains.
Preferred polyesters will be of the family
consisting of high molecular weight, polymeric
1,4-butylene glycol terephthalates or isophthalates
having repeating units of the yeneral formula:
(I~
~(CH2)4--O--C~ ~,C--O }
and mixtures of such esters, including copolyesters
of terephthalic and up to about 30% isophthalic
acids.
Especially preferred polyesters are
polye~hyleneterephthalate, poly(1,4-butylene 70/30
isoterephthalate) and poly(1,4-butylene
terephthalate). Speeial mention is made of the
latter because it is easy to prepare from readily
available materials and crys~allizes at an
especially rapid rate.
3 ~
08CT04963
Illustratively, sufficiently high molecular
weight polyesters of the preferred type wi 1 1 have an
intrinsic viscosity of at least 0.2 and preferably
about 0. 4 deciliters/gram as measured in
o-chlorophenol, a 60/40 phenol -tetrachl oroethane
mixture or a similar solvent at 25-30C. The upper
limit is not critical, but will generally be about
1. 5 dl . tg . Especi al ly preferred polyesters wi l l
have an intrinsic viscosity in the range 0.5 to 1.3.
Suitable aromatic polycarbonate resins are the
polymers derived from a bivalent phenol and a
carbonate pre-product, for example phosgene, a
halogen formate or a carbonate ester. The aromatic
polycarbonate resins preferably possess an intrinsic
viscosity of approximately 0.35-0.75 (measured in
p-dioxane at 30C and expressed in deciliters per
gramO. Suitable bivalent phenols which may be used
for the preparation of ~hese aromatic polycarbonate
resins are mononucleus and multinuclei aromatic
20 compounds which comprise 2-hydroxyl groups as
functional groups which are both directly bonded to
a carbon atom of an aromatic nucleus. Examples of
suitable bivalent phenols are: 2,2-bis(4-hydroxy-
phenyl) propane (Bisphenol A = BPA), resorcinol;
25 bis~4-hydroxy-s-nitrophenyl) methane;
2,2'-dihydroxydiphenyl; 2,6-dihydroxynaphthalene;
bis-(4-hydroxy-phenylsulfone); 5'-chloro-2,4'-
dihydroxyldiphenyl sulphone, 4,4'-dihydroxydiphenyl
ether, and 4,4'-dihydroxy-2,5-diethoxydiphenyl
ether.
In preparing the aromatic polycarbonate resins
it is possible to use two or more different bivalent
phenols or a copolymer of a bivalent phenol with a
glycol or with a polyester with hydroxy group or
acid terminal group. The aromatic polycarbonate
08cq~04963
_ 7 _
resin may also be prepared in the presence of a
dibasic acid. Crosslinked polycarbonate resins as
described in U.S. Patent No. 4,001,184 are also
suitable. It is also possible to use a mixture of
two or more of the ahove-mentioned polycarbonate
resins. The homopolymer derived from bisphenol A is
preferably used as a polycarbonate resin.
Upon exposure $o heat and flames, the binder
material burns, decomposes or experiences reduced
viscosity resulting in the release of the fiber web
allowing ~he web to loft. Generally, the longer the
fiber length for randomly dispersed glass fibers the
greater the web will loft and the greater the web
will protect the substrate. In other words, the
longer the fibers in a randomly dispersed compressed
fiber system, the greater the degree of loft
obtained upon decompression. The c~mpressed
composite layers are made by the binder material and
fibers being randomly dispersed to ~orm an
20 unconsolidated, lofted web, which is then
consolidated by heat and pressure into a solid
continuous form. The pressure causes the fibers to
be compressed, and the heat, in the case of
thermsplastic binder materials, serves to melt the
2s thermoplastic which then flows around the fibers and
upon cooling forms ~ solid matrix which locks ~he
fibers into a compressed state. Suitable compressed
composite layers ~re set forth i n European Patent
Applica~ion 0,148,761 filed January 3, 1985 and
published July 17, 1985.
As mentioned above, the preferred binder
ma~erials are thermoplas-tics. Preferably the
thermoplastic is, prior to dispersion and
consolidation, in the form of a fine powder or
particulate. The plasties may also be in a needle
o ~ J t~ 3
08CT04963
or fibrous form prior to dispersion and
consolidation. The fibers and thermoplastic powder
or particulates can be randomly dispersed to form a
lofted web by any of various well known dispersion
processes including dry blending, aqueous
dispersion, latex dispersion and foam dispersion
processes. Suitable processes are set forth in
Uniked Kingdom Patent 1,129,757, United Kingdom
Patent 1,329,409, European Patent Application
0,148,760, European Patent Application 0,148,761,
U.S. Patent 4,426,470, and U.S. Patent 3,716,449,
all of which are incorporated herein by reference.
Extrusion processes involving the mixing of fibers
and thermoplastics are generally not suitable in
15 that they lead to substantial breakage of the fibers
resulting in fibers of insufficient length for the
desired level of lofting. The above dispersion
processes result in the formation of a web of
randomly dispersed fibers in thermoplastic powder.
The web is initially an unconsolidated web which is
in a generally uncompressed state, lofted, and in
the form of a mat. De~ining the unconsolidated web
as being in a generally X, Y plane, the randomly
dispersed fibers generally have degrees of
2s orientations in e~ch of the Xr Y and Z direction,
th~ Z direction being perpendicular to the XY plane.
While the fibers may be primarily oriented in the XY
plane they generally have some degree of orientation
in the Z direction. Having a degree of orientation
in the Z direction can facilitate the fibers being
in a lofted state giving the web an initial
unconsolidated thickness and a relatively low volume
fraction of glass. Upon being compressed to a
compressed state, the fibers will, due to their high
modulus of elas~icity, exert forces in the Z
g /I. '".' i^3
OE~CT04963
_ g _
direction in an effort to return the web to its
i ni ti al unconsol i dated thi ckness . Thus, when the
unconsolidated web is heated and compressed and then
cool ed, the bi nder matrix upon sol i di f i cati on hol ds
the compressed fibers in a compressed state thereby
providing a relatively thin compressed composite
layer. Later upon exposure of the composi te 1 ayer
to high levels of heat or flames, the binder matrix
mel ts or burns allowing the fi bers to loft in the Z
lo direction thereby forming a thick lofted web of heat
resistant fibers whi ch act as a hea~ and fi re
barrier ~or the underlying substrate.
It is also believed that the lofted heat
resistant fiber web provides reduced oxygen access
15 to the underlying substrate thereby reducing the
substrate's tendency to burn. Additionally, it is
believed that the lofted fiber web provides for more
complete combustion of hydrocarbons passing
therethrough resulting in reduced smoke levels
during burning of the structure as compared to
burning of an unprotected substrate.
Substra~e layers ~or ~he struc~ures of the
present invention include wood substrates and
plastic foam substrates.
The wood substrate layers may be any wood based
material. Specifically, preferred wood based
materials include solid wood, for example pine~ oak,
cedar and fi r boards, parti cl e board, oriented
strandboard, flakeboard and plywood, These wood
products ar~ well known in the building industry.
Plastic substrate layers employed in th~
building industry i ncl ude vari ous i nsul ati ve pol ymer
foams including polystyrene foams and polyethylene
foams, polypropylene foams, polyurethane foams and
crosslinked polyethylene ~oams.
~P ~ 3 IJ ~
08C!T04963
- 10 -
Both the wood substrate layers and the plastic
foam substrate layers need protection from heat and
flames.
The structures have a composite layer attached
to a substrate layer. Suitable means for attaching
the composite layer to the substrate layer in~lude
mechani cal attachments such as clamps, screws,
nails, bracke~s, frames and staples; and chemical
adhesives such as thermoset and thermopla~tic
lo bonding agents i ncl udi ng gl ues and epoxies. The
chemical adhesives are preferred.
Unconsidated webs prior to consolidation have a
desired glass density which is defined as the amount
of glass per unit volume of unconsolidated web.
Preferably the glass density is from 0.03 g/cm3 to
1.5 ~/cm ; more preferably from 0.05 gJcm3 to 0.09
g/cm , and most preferably about 0.07 g/cm3; and
preferably the unconsolidated webs have a thickness
of ~rom 0.2 inch to 5 inches, more preferably from
0.5 inch to 2 inches, and most preferably about 1
i nch . These parameters assi st in assuring that the
compressed composite layer will provide the desi red
level of lofting upon exposure to heat an~ fire.
Compressed composite 1 ayers preferably have
from 35% to 98% by weight fibers based on the total
wei~ht of the composite lay r, morP preferably from
40% to 80% by weigh~ thereof, and m~st preferably
about 50% by weight thereof; preferably from 2% to
65% binder material based on the total weight of the
30 composite layer; more preferably from 2a% to 60% by
wei ght thereof; and mos~ preferably about 50% by
weight thereof. The compressed composite layer
preferably has a thickness of from 0.015 inch to
0.50 inch, more preferably from 0.04 inch to 0.25
inch, and most preferably about 0.08 inch. The
OIBCT04963
compressed composite layer is characterized as
having a thickness of less than 50% of the original
thickness of the unconsolidated web, and more
preferably has a thickness of less than 25% thereof,
and most preferably from 4% to 20% thereof. The
compressed layer upon exposure to excessive heat or
flames will loft to a lofted web thickness which is
preferably a~ least double the thickness of the
original compressed composite layer and which
approaches the thickness of the original
unconsolidated web. This lofting phenomenon all OW5
the compressed composite layer to be thin but upon
exposure to fire allows the fire nesistant fiber web
o~ the compressed l ayer to expand to a 1 ofted 15 thickness which will provide adequate protection tG
the underlying substrate layer. It is preferred
that the fiber web of the compressed layer expands
to a lofted thickness of from 0.25 inch to 3 inches
upon exposure to excessive heat or flames depending
upon the desired level of protection desired. The
excessive heat or flames cause the binder matrix to
release the compressed fibers all~wing the web to
loft. The binder matrix will release the fibers
when ei ther ( i ) the bi nder materi al reaches a
sufficiently high temperature that its viscosity is
reduced to a level low enough to allow the
cumpre~sed fibers to ov~rcome the resistance of the
binder material and thereby expand to a lofted
thickness or (ii) the binder material is
sufficiently degraded or burned to allo~ the matrix
to release the fibers and allow the web to expand to
a lofted thickness.
The composite layers preferably have a low
level of fuel content therein to minimize the heat
generated during burning of the binder matrix. Fuel
08CT0 4 9 63
~ 12 ~
content may be minimized by employing a minimum
amount of binder material in the composite. As
noted above, preferably the binder material is
present at a level of from 2% to 65% by weight based
S on ~he ~otal weight of ~he composite layer, more
preferably from 20% to 60% by weight thereof, and
most preferably about 50/0 by weight thereof; in
addition to minimizing fuel content in the composite
layer, it is also desired to maximize the degree of
lofting achie~ed by compressed composite layer upon
exposure to heat and flames so that the thickness of
the lofted fire resistant fiber web is maximized to
thereby provide maximum protection to ~he underlying
substrate. Lofting can be maximized by maximizing
the fiber loading in a structure. Preferably the
fiber is present in the composite layer at a
concentration of from 35% to 98% by weight based on
the total weight of the composite layer, more
preferahly from 40/0 to 80% by weight thereof, and
most preferably about 50% by weight thereof.
The composite layers may also contain from 1%
to 25% by weight mineral fillers based on the total
weight of the composite layer. Suitable mineral
fillers include titanium oxi~es.
Preferred structures include compressed
composite layer adhered to a wooden substrate layer;
compressed composite layer adhered ~o a wooden
substrate layer which is adhered to an insulative
foam layer; and compressed composite layer adhered
to an insulative foam layer. Other preferred
structures include having a wooden substrate layer
disposed between at least two compressed composite
layers; and an inner uni~ having insulative foam
layer disposed between at least ~wo layers of wood
08Cq!~4963
- 13 -
which wherein the unit is disposed between at least
two compressed composi~e layers.
Another suitable structure has a unit having a
foam layer disposed between a pair of wooden
substrates wherein a composite layer is adhered to a
surface of the unit.
Additionally, the structures may employ more
than one composite layer.
The wooden substrate 1 ayers wi 11 preferably
have a thickness of from 0~10 inch to 3.0 inches,
more preferably from 0.20 inch to 2.0 inches, and
most preferably from 0.20 inch to 1.0 inch The
foam substrate layers will prefe~ably have
thicknesses of from ~.25 inch to 8.0 inches.
The structures of the present invention are
useful as i nteri or and exteri or bui 1 di ng materials
i ncl udi ng usef ul ness as roof i ng, s i di ng, walls,
f 1 oors, cei 1 i ngs, etc.
EXQMPLES
The following examples illustrate the presen~
invention but are not meant to limit the scope
thereof .
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- 14 -
OESCT04963
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08CTû4963
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An important test in the building industry
involves applying a controlled flame to one side of
a sheet material, for example a plywood sheet, and
measuring the time that it takes ~or the temperature
5 at the back side of the sheet to reach a given
temperature, for example 160C. Such tests are
particularly useful when it is desired to protect
certain materials such as insulative foams from
temperatures in excess of 160C. Standard tests
include UBC (Unified Building Code) 17-3. The
following examples used a simplified test which in
practice has corresponded well with thP UBC 17-3
test. The test employed in the following examples
involved holding the s~ructures horizontally over a
vertical flame. The structures employed were
5" X 5" square in dimensions ànd were located 4.25
inches above the base of the flame. The flame was
generated using a Fischer burner and a constant
methane rate throughout the tests. The composite
layer was adhered to the substrate layer by
phenol/formaldehyde resin glue. During testing the
composite layer was located between the substrate
layer and the flame. Thermocouples were placed on
the back side of the substrate layer and in between
the substrate layer and composite layer to measure
the temperatures at those locations during the test.
The tests were conducted in a chamber to control
conditions surrounding the test.
The following structures employed a 0.055 inch
30 thick compressed composite layer which was 50% by
weight glass fibers having a diameter o~ 16 microns
and having in general lengths of about 0.50 inch;
and which was 50% by weight of polybutylene
terephthalate thermoplas~ic binder material. The
compressed composite layers were produced by a ~oam
0 8CT0 4 9 63
- 16 -
dispersion process according to Gatward, et. al.,
U.S. Patent 3,716,449, wherein a lofted randomly
oriented fiber web in the thermoplastic powder was
obtained, the web was then consolidated by applying
heat and pressure thereto, and was then cooled under
pressure to allow the thermoplastic matrix to
solidify around the fibers and hold the fibers in
their compressed state. The lofted web, prior to
consolidation, had a thickness of about 1 inch.
lo Various substrates were protected by the compressed
composite layers and the following examples
illustrate the degree of protection provided by the
compressed composite layers of the present
invention.
1 7
08CT0 4 9 63
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085:~T04963
- 18 -
Examples 11 to 15 i 11 ustrate the degree of
protecti on obtained by compressed composites
employing 50% by weight polybutylene terephthalate
as the binder matrix based on the total weight of
the composite layer and 50% by weight glass fibers
based on the total weight of the composite layer.
The glass fibers had a diameter of 16 microns. The
structures employed had the 0.055 ineh thick
composite layer adhered to a 0.25 inoh thick
oriented strand board substrate layer. The
following examples set forth the time for the
backside of the structure to reach 160C after
initiation of exposure of the structure to the
flame. The compressed composite layer was located
between the flame and the strandboard substrate
layer.
Examples 16 to 20 illustrate for various glass
fiber lengths the temperature between the composite
layer and the substrate layer at 6 minutes after the
initiation of the burn test. The structures of
examples 16 to 20 are similar to the structures of
examples 11 to 15.
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08CT04963
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