Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FDN-1791
FLAME RETARDANT BTTUMEN
BACKGROUND OF THE INVENTION
Roofing sheets are generally supplied in rolled up
form for use in the formation of roofing membranes wherein
overlapping sections of the material are used to form one
or more plies of the finished roofing membranes. In
addition they may be used on sidewalls of buildings. Such
roofing membranes and systems are used primarily on
commercial buildings ox buildings of low slope by reason of
their durability and comparatively low cost. One type of
roofing sheet which is in demand for economical
installations is a modified asphalt sheet. However, since
modified asphalt is not fire resistant, it has been the
practice to manufacture the sheet with a glass mat
reinforcement and to cover it with a separate flame
retardant composition such as a glass cap sheet or
coating. Obviously, this procedure reguires several time
consuming steps to complete the roofing installation.
Accordingly, it is an object of thus invention to
simplify the aperation necessary for providing a fire
retardant roofing membrane.
Another object is to eliminate the necessity for
a glass mat reinforcement either alone or in addition to
the polyester reinforcment in the sheet and to provide a
fire reta~dant roef covering with a material which
incorporates fire r~tardancy, thus eliminating the need for
membranes of different composition and top coating
operations.
These and other objects will become apparent from
those skilled in the art from the following description and
disclosure.
CA 02022151 1999-10-08
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THE INVENTION
In accordance with this invention there is provided a
modified asphalt sheet which is impregnated, i.e. saturated or
coated on its upper and/or lower surfaces with a composition
comprising (a) between about 35 and about 60 wt. o petroleum
asphalt or an asphaltic blend having a Brookfield viscosity at
210°F. of between about 500 and about 4000 cps, a penetration at
77°F. (100 g., 5 seconds, mm/10) of from about 20 to about 350
dmm and a softening point of from about 80° to about 200°F; (b)
between about 2 and about 30 wt. o of a thermoplastic
copolymeric styrene modifier and (c) between about 35 and about
50 wt. o of colemanite, combined to provide 1000 composition.
In the above composition, the asphaltic component is
more desirably used in a concentration of from about 45 to about
60 wt. % and is preferably one having a viscosity of from about
1500 to about 3000 cps; a penetration of from about 80 to about
200 dmm and a softening point of from about 100° to about 150°F.
Such asphalts include roofing flux, straight reduced, thermal
and air blown asphalts, mopping asphalt, liquid cut-back
asphalts, etc. It will be apparent that asphalts of relatively
lower penetration and higher viscosity can be employed when
diluted with a cutting oil, such as for example, gas oil, to
provide the asphaltic component having properties within the
above ranges.
Suitable modifier components are those conventionally
employed for saturation of polyester roofing mat, and include
from about 5%-95o to about 40%-60o by weight blends of isotactic
polypropylene having a melt flow of from about 2 to 200 and
atactic polypropylene homopolymer or copolymer containing up to
40% ethylene comonomer. An alternate modifier component which
can be employed in the present composition is a synthetic
polymer such as polyisobutylene, polybutylene or blends thereof.
CA 02022151 1999-10-08
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These modifiers generally comprise between about 2 and
about 30 wt. % of the flame retardant composition. Still
another alternate is a styrene-butadiene,
styrene-ethylene-butadiene-styrene,
styrene-butadiene-styrene block copolymers or
styrene-butadiene-rubber containing from about 10 to about
50 wt. % styrene, preferably from about 25 to about 35 wt.
% styrene. When the styrene containing modifier is
selected, the copolymer generally comprises between about 2
and about 20 wt. %, preferably between about 8 and about 15
wt. % of the composition.
Colemanite is a natural blend of hydrated oxides
as represented by a particular type of calcium borate
generally containing between about 30 and about 55%
B203 and between about 20 and about 35% CaO. This
mineral may also contain up to about 12% other oxides such
as silicon dioxide, aluminum oxide and magnesium oxide.
The colemanite is preferably used in the present
composition in a concentration of from about 10 to about
50% and is generally employed as granular material having a
mesh size of from about 75% to about 80% minus 200 mesh
screen.
A particular advantage of colemanite is its high
cost effectiveness and availability over other borate
compounds and compositions containing colemanite within the
above ranges can be easily applied to polyester mats to
achieve a Class A rating in the ASTM E-108 and UL 790 fire
tests. Consequently, it is not necessary to apply a
separate fire retardant top coating to the modified asphalt
membrane. Also, the need for glass mat reinforcement is
completely eliminated. Thus, the cost of the completed
roof is greatly reduced and greater fire protection is
afforded by coverage with the present inherently fire
resistant roofing ply or plies. It is to be understood,
CA 02022151 1999-10-08
4
however, that the present composition is also suitable for
coating or impregnation of other reinforcing mats such as glass
mats, glass/polyester composites, etc. Typically a roofing
material may comprise about 40 to 95 wt. o of a composition of
the invention.
The roofing membrane can be a mono or multi ply
structure depending on the desired thickness of the roof
covering. Generally, a thickness of from about 0.07 to about
one inch is sufficient to provide good weathering preferably
from about 0.07 to 0.25 inch, particularly between about 0.12
and about 0.2 inch.
The method of coating a reinforcing mat is
conventional and includes dipping, spraying, soaking or
mechanical coating with a doctor blade or similar device. When
coating a surface of the mat, the present composition is
generally applied in a thickness of from about 0.05 to about 0.5
inch. Saturation of the mat provides inherent fire retardant
throughout the felt.
The present composition is easily prepared by mixing
the components in any order at a temperature of from about 100
to about 500°F. for a period of from about 1 to 24 hours,
preferably at about 325-400°F. for 2 to 6 hours. The composition
is then applied to the mat at about the same temperature to
provide a product suitable for installation. The roofing sheet
obtained shows no deterioration in flexibility so that it can be
easily unrolled for overlaying a roof deck and can be easily
handled in roofing construction.
Many methods of roofing can be employed for the
purposes of this invention. For example, the present roofing
sheet can be utilized as the sole roof covering over the entire
deck or a base and top covering with instant roofing sheet can
be combined with intermediate roofing layers of a different
composition, e.g. an impregnated or non-impregnated glass mat.
CA 02022151 1999-10-08
4a
Also, alternate layers of roof covering can be employed. The
specific roofing procedure for installation is conventional and
need not be further discussed.
.. g
Having generally described the invention,
reference is now had to the following examples which are
provided to illustrate preferred embodiments but which are
not to be construed as limiting to the scope of the
invention as more broadly discussed above and as defined in
the appended claims.
EXAMPLE 1
The following ingredients for the flame retardant
composition were introduced into a metal container and
mixed for 4 hours at 380 °F.
Ingredients wt. %
(1) AC-5 Asphalt 57.5
Isotactic polypropylene 3.5
(melt flow 60-90)
Atactic polypropylene/polyethylene blend 20.0
Polyethylene (melt flow 75-35) 6.0
Colemanite 13.0
(1) Per ASTM D3381 Table 2
The above melt was applied to a 12x20 inch sheet
of polyester roofing mat (0.038" thick) by coating an a 2
roll mill to build a thickness of 0.157". The resulting
product was then subjectedwto a flame test which comprised
subjecting a 4x8 inch sample of the above, mounted on a
1''/ft slope to the frame of a propane burner fox 90
seconds. The results of this test are as reported in
Table I.
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A full sized roll of roofing sheet having the
above composition was prepared and sent to Underwriters
Laboratories (Northbrook, Illinois) for fire retardancy
testing and quality classification The above formulation
was assigned a Class A rating, indicating minimal flame and
char damage, substantially no sheet flow coupled with high
flame extinguishing properties.
When 7 wt. % polyisobutylene is substituted for
isotactic polypropylene in the above composition, the
resulting product has substantially the same beneficial
properties.
L'Y~MDT.F 7
The following ingredients for the flame retardant
composition were introduced into a metal container and
mixed for 4 hours at 380 °F.
Ingredients wt.
(2) Asphalt (Penetration 130 dmm) 52.1
(3) Krat~n*1101 4~9
( 4 ) Kraton~ 1102 3 . 0
Colemanite 40.00
(2) softening point 120°F. (3) 31/69 styrene-butadiene
copolymer, 0.94 specific gravity, Brookfield viscosity
(toluene solution) at 77°F, 4,000 cps (25 wt.% polymer)
(4) 28/72 styrene-butadiene copolymer, 0.94, Brookfield
viscosity (toluene solution) at 77°F, 1,200 cps (25 wt. %
polymer).
*Trade-mark
CA 02022151 1999-10-08
_ 7 _
The above melt was applied to a 12x20 inch sheet
of polyester roofing mat (0.038 " thick) by coating on a 2
roll mill to build a thickness of 0.157 inch. The
resulting product was then subjected to a flame test which
comprised sujecting a 4x8 inch sample of the above, mounted
on a 1"/ft slope to the flame of a propane burner for a 90
seconds. The results of this test are as reported in
Table I.
A full sized roll of roofing sheet having the
above composition was prepared and the was then tested for
fire retardancy by Underwriters Laboratory as described
above. This sheet was given a Class A rating.
TABLE I
90 Second Burn Test
Product Tested Char Formation Flow
Example 1 excellent none
Example 2 very good very slight
Commercial Sample excellent ncne
Manville Dynakap*FR SBS
Commercial Sample very good none
Siplast*Paradiene*FR SBS
*Trade-mark
