Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to an intumescent composite comprising
fire retardant materials having a restrain~ng layer laminated thereto to dimen-
sionally control the refractory char produced upon heating the laminated
intumescent composite. The intumescent composite exists in a flexible rubbery
form to the extent that it is not rigidized by the restraining layer. After
exposure to intense heat or fire, the restrained composite intumesces and
becomes a rigid char which has been dimensionally controlled by the restraining
layer.
Prior art devices such as are disclosed in McMartin, United States
Patent No. 3,864,883 and Bradley et al., United States Patent No. 4,061,344,
have used intumescent material in the area of fire, vapor and smoke barriers.
Canadian Patent No. 1,118,948, issued February 23, 1982 to Minnesota Mining
and Manufacturing Company, relates to one type of flexible heat-expanding fire
retardant composite materials with the intumescent component within an elasto-
meric binder. These composites have no directional control of their expansion
and thus are optimally used within confined spaces. They are most effective
in poke-through devices.
The present invention comprises a layer of intumescent sheet material
to which a restraining layer is laminated. Intumescent composites which are
laminated with restraining layers have been shown to exhibit dramatically dif-
ferent expansion properties when compared to unrestrained intumescent sheets.
It has been unexpectedly found that when an intumescent composite of the
present invention is heated or burned in a fire at a temperature greater than
about 110C, expansion of the composite occurs in a controlled directionali~ed
manner. The intumescing composite expands in a direction substantially per-
pendicular to the restraining layer rather than expanding isotropically as
would be the case with an unrestrained intumescent sheet.
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The composites of the present invention, in conjunction with suitable
application methods, provide a superior intumescent barrier for use in sealing
penetrations through walls, floors, partitions and ceilings from smoke, fire,
gas and water passage, since the char formed during the intumescent reaction
can be generated in a directionalized manner to assure that the penetration
cavity is optimally filled. In addition, the ability of the composites of the
present invention to expand, when exposed to heat or fire, in a directionalized
manner so as to optimally fill penetrations, allows for lower cost fire protec-
tion devices.
In addition, the intumescent composites of the present invention can
have holes punched in them and can be used in fire protection applications where
air circulation is desired. In the event of a fire, the direction of expansion
of the intumescent composite is controlled by the restraining laycr, so that
the holes are filled and an effective fire barrier is provided.
Rroadly stated, according to a first broad aspect of the present
invention there is provided a flexible intumescent composite for use in sealing
penetrations through walls, floors, partitions and ceilings comprising a layer
of intumescent sheet material at least one major exterior surface of said in-
tumescent sheet material having a restraining layer laminated thereto, said
intumescent material being capable of expansion when subjected to elevated
temperatures, and wherein said restraining layer (a) will not decompose or
soften before the underlying intumescent sheet material has had a chance to
expand; (b) has sufficient tensile strength to resist tearing during expansion
of the intumescent sheet material; and (c) is bondable to the underlying intumes-
cent sheet and resists delamination throughout the expansion process; when said
composite is subjected to temperatures over about 110C, wherein said restrain-
ing layer will withstand temperatures of about 150C before it begins to
I ~ ~8969
soften or degrade, and wherein said intumescent composite has sufficient flex-
ibility to allow said intumescent composite to be helically wrapped so as to
fit into cylindrical penetrations or be wrapped around cable trays.
According to a second broad aspect of the invention, there is pro-
vided a method of controlling the expansion direction of an intumescent sheet
material when said material is subjected to elevated temperatures comprising
laminating at least one major exterior surface of said sheet of intumescent
material with a restraining layer which (a) will not decompose or soften before
the underlying intumescent s:heet material has had a chance to expand; (b) has
sufficient tensile strength to resist tearing during expansion of the intumes-
cent sheet material; and (c) is bondable to the underlying intumescent sheet
and resists delamination throughout the expansion process; when the composite
of said intumescent sheet materi.al a.nd said restraining layer is subjected to
temperatures over about 110C, and wherein said restraining layer will with-
stand temperatures of about 150C before beginning to soften or degrade.
The invention will now be described in greater detail with reference
to the accompanyi.ng drawings, in which:
Figure l is an enlarged sectional view of the intumescent composite
of the present invention;
Figure 2 is an exploded perspective view of one embodiment of a fire
barrier device using the intumescent composite of the present invention with
parts thereof shown in section;
Figure 3 is an enlarged sectional view of one embodiment of the
intumescent composite of the present invention;
Figure 4 is an enlarged sectional view of a disc comprising intumes-
cent sheet material coated with a nonrestraining layer;
Figure 5 is an enlarged sectional view of the disc of Figure 4, after
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~ 1 6 ~)? ~3 6 9
it has intumesced;
Figure 6 is an enlarged sectional view of a disc comprising the in-
tumescent composite of the present invention; and
Figure 7 is an enlarged sectional view of the disc of Figure G,
after it has intumesced.
Referring now more particularly to the drawings, the composite, in
its simplest form, cornprises a sheet 11 of intumescent material with a restrain-
ing layer 12 laminated thereto. The preferred intumescent sheet material 11
is a flexible heat-expanding, fire retardant composition comprising an intumes-
cent component in granular form such as hydrated alkali metal silicate~ an
organic binder component, an organic char-forming component such as phenolic
resin and fillers. Such a composition is disclosed in above-mentioned Canadian
Patent No. 1,118,948. This composition is a flexible rubbery material in its
unexpanded state, but once subjected to temperatures on the order of 110C.
and higher, intumesces up to 10 times its original volume and becomes a rigid
char which is capable of sealing penetrations in which it is contained against
the passage of smoke, vapors and water. Of course, other intumescent materials
such as Palusol ~9commercially available from BASF, and expantrol ~ commer-
cially available from the 3M Co., can be satisfactorily utilized and fall with-
in the scope of the present invention.
The following requirements for the restraining layer 12 have been
determined:
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(1) it should not decompose or soften before the
underlying intumescent sheet material has had a
chance to expand, i.e., it should withstand
temperatures of about 150C. before it begins to
soften or degrade;
(2) it should have sufficient tensile strength to
resist tearing during expansion of the
intumescent sheet material; and
(3) it should be bondable to the underlying
intumescent sheet and resist delamination
throughout the expansion process.
Restraining layer materials that meet the above
criteria include metal foils, sheets, and screens made
from aluminum, copper, steel, and lead; heavy paper and
cardboard such as Kraft-type paper; high temperature
rubber and plastic sheets such as are made from silicones
and epoxies; screen and cloth made from inorganic fibers
such as fiberglass, and high temperature organic fibers
such as aramid.
Bonding of the restraining layer to the
intumescent sheet material is preferably accomplished by
laminating the restraining layer to the intumescent sheet
prior to vulcanization of the preferred rubbery
intumescent material. Vulcanization of the restrained
~5 intumescent composite results in a strong bond being
formed between the restraining layer and the intumescent
sheet. Alternatively, certain cements and adhesives which
have adhesive-softening points above the temperature at
which the intumescent material expands, can be satisfac-
torily utilized. Exemplary cements and adhesives include
those made from silicones and epoxies.
To demonstrate the effectiveness of the
restraining layer in directionalizing the expansion of the
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intumescent sheetl the following tests were run and are illustrated in Figures
4-7.
Discs were made of 6.35 mm thick intumescent sheet material prepared
according to above-mentioned Canadian Patent No. 1,118,948. The intumescent
sheet material comprised about 25 percent by weight polychloroprene commer-
cially available as Neoprene~ W from DuPont, about 56 percent by weight hydrous
sodium polysilicate commercially available as "Britesil~H24" from Philadelphia
Quartz Co., about 11 percent by weight phenolformaldehyde commercially avail-
able as "Varcum~ 5485" from Reichhold Chem. Co., and about 8 percent by weight
silica commercially available as "Min-U-Sil~" from Pennsylvania Sand and Glass
Co., which had been compounded in a Banbury mixer, milled together to a flexible
rubbery composition, and sheeted out. Each disc was 50.8 mm in outside dia-
meter and a 10.2 mm diameter center hole 16 was cut in each. The intumescent
disc in Figure 4 was vulcanization bonded, i.e., bonded during the vulcaniza-
tion process, on both sides with a 0.127 mm Neoprene6~ rubber coating 15. This
rubber coating is nonrestraining, since it softens in the same temperature range
as the intumescent sheet. The intumescent disc in Figure 6 was vulcanization
bonded on both sides with a restraining layer of 0.064 mm aluminum foil 12.
Both discs were expanded at 350C for 15 minutes in an air oven. Ihe overall
volumetric expansion for the disc of Figure 4, illustrated after expansion in
Figure 5, was 10.3X. The corresponding amount of expansion for the disc of
Figure 6, illustrated after expansion in Figure 7, was 9.3X. The expanded char
shown in Figure 5, intumesced substantially uniformly in all directions from
its unexpanded state shown in Figure 4. However, quite dramatically, the
expanded char shown in Figure 7, which had been restrained with a vulcanization
bonded layer of aluminum foil 12, completely closed off the hole 16 and expanded
substantially in the direction perpendicular to the restraining layer. Expan-
``
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sion in a direction perpendicular to the restraining layer was 4.5X for therestrained composite as opposed to 2.7X for the unrestrained composite. These
tests illustrate that the restraining layer 12 was quite effective in direc-
tionalizing the expansion of the intumescent composite, enabling the punched
hole to be filled. These tests also illustrate that the restrained intumescent
composite, when fired, expands substantially in a direction perpendicular to
the plane of the restraining layer.
Applicants have unexpectedly found that when the restrained intumes-
cent composite structure of the present invention is heated or burned at a
temperature greater than about 110C expansion occurs in a controlled, direction-
alized manner. During heating the intumescent composite becomes soft and the
gas generated in the intumescent process expands the composite. While Appli-
cants do not wish to be bound by any theory, it is thought that the restraining
layer 11 prevents gas passage and forces the gas in the intumescing composite
to be relieved two dimensionally, i.e., perpendicularly to the restraining
layer rather than expanding isotropically as would be the case with an unrest-
rained intumescent sheet.
A particularly preferred use of the composite of the present invention
is illustrated in Figure 2.
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Referring now more part~cularly to ~igu~e ~,
intumescent composite 13 is a flat sheet of intumescent
material 11 having a restraining layer 12 such as that
disclosed by the present invention laminated to one side,
and an elastomeric material 15 such as Neoprene~ rubber
coated on the other side. The elastomeric coating need
not be a restraining layer and is utilized to reduce
degradation of the intumescent sheet material by moisture.
Composite 13 is cut into a parallelogram configuration and
helically wrapped to form a sleeve which conforms to the
interior of the cylindrical penetration 10. A
partition 17 is provided in the device of Figure 2 and
comprises intumescent material 11 having a restraining
layer 12 laminated to both sides. The expansion direction
of the intumescent composite is effectively controlled by
restraining layer 12. E`or example, upon exposure to
temperatures of above about 110C., composite 13 and
partition 17 expand substantially perpendicular to the
plane of restraining layer 12 such that the interior of
penetration 1~ is ~illed with thc expanded composite.
In certain industrial and utility plants,
especially nuclear power plants, it is necessary to fire
protect power and process control cables used in running
the plant. For example, nuclear power plants require
redundant sets of control cables carried in cable trays,
and each set of control cables must be individually
protected for one hour so that the cables do not short out
in the event of a fire. Present systems utilize ceramic
fibers or refractory boards t:o insulate the cable trays~
When these products are used to wrap a tray, they trap the
heat generated in the cables making it necessary to derate
(lower the amperage of) the cables. Use of the composite
of the present invention as an enclosure for cable trays
reduces the degree to which it is necessary to derate the
cables. A layer of the composite 13 with small holes 16
in it, as illustrated in Figure 3, can be wrapped around a
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tray and allows for free circulation of cooling air, thus
avoiding severe derating problems. In the event of a fire,
the holes 16 are quickly sealed off by the expanding char
since the char is generated in a direction ~o as to fill
the punched holes. The composite illustrated in Figure 3,
has a nonrestraining elastomeric layer 15 on one side to
reduce degradation of the intumescent sheet material 11 by
moisture, and a restrainin~ layer 12 laminated to the
other side. When the composite is wrapped around a cable
tray, the elastomeric layer is closest to the tray and the
restrained layer is on the exterior of the wrapped cable
tray.
The following example illustrates the
effectiveness of the restraining layer in directionalizing
the expansion of the intumescent sheet.
Example 1
4.06 mm thick intumescent sheet material was
prepared and divided into four lots.
The intumescent sheet material comprised about
25 percent by weight polychloroprene commercially
available as Neoprene~ W from DuPont, about 56 percent by
weight hydrous sodium polysilicate commercially available
as "Britesil H24" from Philadelphia Quartz Co., about
11 percent by weight phenolformaldehyde commercially
available as "Varcum 5485" from Reichhold Chem. Co., and
about 8 percent by weight silica commercially available as
"Min-U-Sil" from Pennsylvania Sand and Glass Co., which
had been compounded in a Banbury mixer, milled to~ether to
a flexible rubbery composition, and sheeted out. In each
lot a different layer was bonded to ~he sheet. In the
first lot, a nonrestraining layer oE 0.127 mm Neoprene~
rubber was laminated and heat (vulcanization) bonded to
both sides of the 4.06 mm thick intumescent sheet. In the
second lot a restraining layer of 0.25 mm thick Yorkite~
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paper was laminated and heat (vulcanization) bonded to
both sides of the intumescent sheet. In the third lot, a
restraining layer of 0.025 mm aluminum foil was heat
bonded to both sides of the intumescent sheet. The fourth
lot had a restraining layer of 0~064 mm aluminum foil heat
bonded to both sides. From each lot five partitions were
cut, 114 x 178 rnm in size. The five partitions from each
lot were fit into a rectangular penetration, 102 x 114 mm,
cut into a 127 mm thick concrete slab. The 114 mm length
of each partition was inserted parallel to the 114 mm side
of the concrete opening and the five partitions divided
the penetration into six equal parts. Nine 6.35 mm
diameter cables were run through the device between the
partitions. The concrete slab was placed upon a gas fired
kiln and the device heated to 927C in approximately one
hour. Temperature measurements were made of the furnace
temperature and the temperature at the center of the
penetration at the concrete level. All four lots were
tested in the above manner. Results are shown in Table 1
and clearly indicate the superiority of the intumescent
sheet laminated with a restraining layer as herein
defined.
Table 1
Temperature Percent
1 hour tC)Penetration
Number Laminated Layer Furnace Surface Filled
1 Neoprene~ 927 127 60
2 Yorkite~ paper 927 35 95
3 0.025 mm Aluminum 927 21 99
4 0.064 mm Aluminum 927 71 95
