Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
`` ~260653
This invention pertains to modified asphalts.
In one of its more specific aspects, this invention
pertains to asphalts modified with synthetic waxes to form
compositions particularly suitable as coatings and saturants.
It i.s well known i.n the art oE roofing shingle
production, to employ aspha~t-based compositions as saturants
on base materials such as felt, glass fibers, asbes-tos and
the like. As extenders, it is customary to include in the
coating certain filler materials which increase the quantity
Of material saturatable by the asphalt, which materials
act to absorb wear on the shingle. Such fillers, however,
at to increase the viscosity of the asphalt making it less
penetratable of the base materials and requiring that the
application of the asphalt to the base materials be made
at higher temperatures to compensate for the increase in
viscosity of the asphalt upon addition of the filler.
It is also well known in the art tha-t various
materials can be blended wi-th asphalt to lower the viscosity
at processing temperatures, thereby enabling easier processing.
For example, in U.S. Patent 4,282,038, to Earing, gilsonite,
a naturally occurring asphalt, is modified by the addition
of a process oil to reduce the viscosity of the asphalt
during processing. It is also known to add waxes to asphalt
to provide viscosity control and improve shape retention
of asphalt articles at elevated temperatures. For example,
U.S. Patent 3,808,164 to Gulino et al teaches the use of
dozens of materials to be blended with asphalt to reinforce
the asphalt material and help retain its shape.
One of the problems with commonly employed ma-terials
for blending with asphalts is that those materials seeking
to reduce the viscosi-ty for processing purposes leave the
asphalt too soft for practical operation as a product. Also,
those additives which make the asphalt harder during temper-
atures normally encountered in the use of the asphalts tend
to make the asphalt too viscous for acceptable processing.
This invention is directed to the solution of that
problem by providing an asphalt blend which has an increased
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softening point over typically blown coating asphalts, while
having an acceptably 1OW viscosity at elevated processing
temperatures.
According to this invention there is provided
a composition comprising a petroleum-derived asphalt and
up to about 10 percent by weight of bis-stearoylamide.
Also, in accordance with this invention, there
are provided compositions, including roofing shingles, comprising
the asphalt and bis-stearoylamide composition.
In a preferred embodiment of the invention, the
composition contains from about 2 to 6 percent by weight
o~ the bis-ste'~roylamide.
The accompanying drawing is a graph of viscosity
versus temperature for a typically blown asphalt and for
an asphalt blended with bis-stearoylamide according to the
principles of the invention.
The invention is applicable to natural and petroleum-
derived asphalts including straight-run Eractionation-derived
asphalts, crac~ed asphalts, asphalts derived from processing
such as blown asphalts, propane deasphalting, steam distillation,
chemically modified asphalts, and the like. In a preferred
embodiment, the invention is applicable to asphalts for
shingle production having a ring and ball softening point
of about 143F.
The bis-stearoylamide can be mixed with -the asphal-t
in any amount suitable to reduce the viscosity of the asphalt
to that viscosity desired for the ultimate blend. Generally,
the bis-stearoylamide will be introduced into the asphalt
in an amount up to about 10 percent by weight and preferably
in an amount within the range of from about 2 to about
6 percent by weight of the blend of the two materlals. The
bis-stearoylamide can be introduced into the asphalt in
any suitable manner, for example, as a solid into a solid
o~ liquid, or as a liquid into a solid or liquid, the addition
being made at any suitable temperature. The bis-stearoylamide
can also be added in an amount sufficien-t to increase the
softening point without significantly al-tering the viscosity
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oE the asphalt.
The bis-stearoylamide used in the invention preferably
has a softeniny point greater than 260F, and has the following
chemical composition:
7H35 lCI NH-CH2-CH2-NH-C-C17H35
O O
The final combination of bis-stearoylamide and
asphalt can be diluted with any suitable diluent. Further,
any combination of other materials such as aggregate
asbestos, glass, and the like can be incorporated into the
combination.
Application of the asphalt and bis-stearoylamide
to the base material is made in the usual manner, with or
without the addition of fillers.
It has been found that the addition of between
2 and 6 percent of bis-stearoylamide to asphalt greatly
improves the weatherability of asphalt shingles~ Although
some slight improvement might have been expected, the improve-
ment was so great that it exceeded any expectation. The
term "weatherability" is a term that is well understood in
the ar-t as indicating durabili-ty or resistance to weather
conditions. Webster's Third New International Dictionary
deines "weatherability"as the"capability of withstanding
weather".
The -Eollowing Examples illustrate the invention.
EX~MPLES
RooEing shi~gles for weather -testing were prepared
by coating a conventional shingle base mat with control
asphalt compositions (1) and (2). Composition (1) comprised
coating grade asphalt and 62~ .filler while composition t2)
comprised the same coating grade asphalt with ~5% of the
same filler as used in (1). Three specimen shingles were
prepared using each of the asphalt coating compositions
; (1) and (2).
.
~2~ i3
Specimen shingles were prepared in the same manner
using asphalt coating compositions (3) and (4). Composition
(3) comprised the coating grade a.sphalt, 3% Glyco Wax (bis-
stearoylamide) and ~5~ filler while composition (4) comprised
the coating grade asphalt, 3% Glyco Wax and 70% filler.
Three specimen shingles were prepared using each of compositions
(3) and (4).
The specimen shingles were then subjected to a
standard weathering test with the following results, the
irldicated cycle ranges representing the greatest number
of cycles recorded beore failure had occurred:
24 Hour Cycles
15 COating Specimen
Composition 1 . 2 3 Average
-
1 62.5- 65.4 62.5- 65.4 62.5- 65.4 64.0
2 55.2- 58.5 51.0- 55.0 55.2- 58.5 55.6
3 109.9-112.4 89.5- 92.9 97.0-100.0 100.3
4112.4-119.5 119.5-121.5112.4-119.5 117.5
The above resul-ts show that the bis-stearoylamide
modified asphalt compositions ~Nos. 3 and 4~ improve the
weatherabi.lity of roofing shingles substantially by approx-
imately 100% before failure when compared with the convent.ionalunmodiied standards (Nos. 1 and 2). This remarkably improved
weatherability couId not have been predicted from the prior
art and was unexpected.
It has been found that the composition of the
invention greatly changes the viscosity/temperature curve
as shown in the drawing. The solid line indicates the proper-
ties of a partially blown asphalt modified with 3 percent
by weight bis-stearoylamide, the blend having 70 percent
filler and a softening point of 225F. The dashed line
shows the properties of partially blown asphalt without
-the bis-stearoylamide modifier, but having 70 percent filler
and a softening point of 170F. The do-tted line indicates
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the properties oE a fully blown, unmodified asphalt with
61 percent filler and a softening point oE 225F. As can
be seen, the modification increa`ses the softening point
in the lower temperature rarlges without significantly lowering
5 the viscosity. Preferably, in the lower temperature ranges
o from about 110F to about 230F the viscosity drops from
about g,000,000 poise to about 11,000 poise. Also, it can
be seen from the drawing that the viscosity drops rapidly
once an elevated temperature is reached. Preferably, in
lO the elevated temperature range of rom about 230F to about
265F, the viscosity drops from about ll,000 poise to about
325 poise.
The composition of this invention can be used
for numerous applications. For example, the composition
15 can be used to coat a fiberglass board having a density
of Erom about 2 to about 12 pounds per cubic foot. Such
boards are suitable for numerous proposes, including, without
limitation, roof insuIation boards and basement wall insul-
ation boards. Another suitable use for the composition
20 of the invention is in sacrificial electrical anodes used
in cathodic protection devices.
Another improtant use for the composition of the
invention is as an undersealer in a hi.ghway constructionO
A problem in the maintenance of highways is that the supporting
25 soil beneath the highway becomes eroded underneath joints
or cracks in the highway. In order to put back in place
support for the highway, an asphalt undersealer is pumped
into a position underneath the join-t or crack.
Another important use of the composition of the
30 invention is in treating or coating the surface, joints
or cracks in pavements. Pavements are broadly defined as
highways, bridge decks, parking lots, driveways, runways,
e-tc. The increased softening point of the composition makes
the composition tougher in the coating or sur:Eacing application,
35 whi.le enabiling a lower viscosity at processing temperatures
for the addition of filler materials and other modifiers.
The composition of this invention can also be used as an
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adhesive and as a dust palliative. It is also suitable
for use as a watexproofing material, particularly for use
on basement walls.
The material is outstandingly adapted to forming
a laminate by intimately bonding it to a flexible sheet-
like support, for example, a thermoplastic film such as
a polyamide, polyester or polyolefin.
The asphalt of the invention can be used as a
pitch substitute for such uses as pipe coatings, board saturants,
and the manufacture of clay pigeons.
The composition described herein, and the products
made from that compositionr result in a changing of the
temperature/viscosity relationship in a way not expected
by the inventor. This results in a greatly improved asphalt
for numerous uses, including in particular, roofing applications.
This resuIts in a processing difference which enables the
conversion of asphalts into coating grade asphalts wi-th
only a minor amount of blowing and mixing, rather than the
extensive amount of blowing required in a typically blown
asphalt.
