Note: Descriptions are shown in the official language in which they were submitted.
CA 02862303 2014-09-05
TITLE: ROOFING ASPHALT COMPOSITION AND METHOD FOR THE
PRODUCTION OF A ROOFING ASPHALT COMPOSITION USING CATALYTIC
OXIDATION
INVENTORS: HUA QIN LIU, VU NGUYEN, RENE DUFRESNE
FIELD
[0001] The present disclosure broadly relates to a roofing asphalt
composition. More specifically, the present disclosure relates to a roofing
asphalt
composition prepared from paving grade asphalt and a method for the
preparation of
same.
BACKGROUND
[0002] The following is not an admission that anything discussed below is
part
of the prior art or part of the common general knowledge of a person skilled
in the
art.
[0003] There are many applications for bitumen (which can also be referred
to
as asphalt). For example, asphalt may be used for waterproofing products or
articles, such as roofs, buildings, boats, shingles, roofing felts, roofing
sheets or
roofing membranes, as well as for paving roads.
[0004] Asphalt shingles are generally the primary roofing materials for
residential graded roofs. Asphalt shingles may comprise either organic felt
materials
or glass fiber reinforcing mats which are saturated or encapsulated with
bitumen or
asphalt to make them waterproof. In general, asphalt shingles are for steep
slope
roofing whereas modified bitumen membranes are for low slope roofing.
[0005] Asphalts for using in roofing applications have different
requirements
than asphalts for using in roads. Road asphalts typically fail due to low
temperature
cracking, repeated loading that can result in rutting and fatigue cracking,
and water
penetration that can result in physical damage due to repeated freeze/thaw
cycles.
In contrast, roofing asphalts typically fail due to thermal shock caused by
repeated
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heating and cooling cycles, low temperature cracking and loss of aggregate due
to
flow.
[0006] When used in roofing applications, conventional asphalt
compositions
obtained through oxidation of asphalt which meets ASTM-D-946, ASTM-D-3381 or
ASTM D-6373 specifications have limited flexibility and weatherability,
causing early
failure of roofing shingles. Accordingly, while similar parameters may be used
to
classify a roofing asphalt and a paving asphalt, e.g., penetration, viscosity,
softening
point, and the like, the specification for a paving asphalt is different to
the
specification for a roofing asphalt.
[0007] Using a particular crude oil, only certain grades of asphalt may be
obtained. The asphalt grade which may be obtained will depend, inter alia,
upon the
processes used to prepare the asphalt and the additives which are included.
[0008] One additive that has been suggested for use in the preparation of
asphalt is waste rubber products, such as tires or tubes. Incorporating waste
rubber
products into asphalt would allow the rubber to be recycled. However, there
are a
number of significant obstacles related to such use. Scrap tires contain
different
types of vulcanized rubber, for example polyisoprene, polybutadiene, styrene-
butadiene, butyl, ethylene-propylene-diene, as well as fillers, plasticizers,
surfactants
and the like. Moreover, tires typically contain a significant number of
different
elastomers. Accordingly, waste rubber is not a single chemical compound but is
a
mixture of various compounds, the composition of which can vary from one tire
to
another.
[0009] Furthermore, because of the cross-linking of the polymeric material
that
takes place by the vulcanization process with sulfur or polymeric sulfur
derivatives,
ground rubber or crumb rubber does not disintegrate readily. The additional
chemical bonds created during this vulcanization render impossible the
complete
dissolution of the polymer in hot bitumen, thus causing problems of stability
of the
material.
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[0010] In
addition, mixtures of bitumen and rubber are not homogeneous and
form two phases of different density which are partially dispersed in one
another.
The system tends to decant and causes the upper layers, which have a lower
density, to be constituted of polymer, while the lower layers, which have a
higher
density, are constituted of bituminous material. Therefore, if natural rubber
or
"polymers" are used, they will constitute part of the lower density layer and
will thus
accumulate at the surface. Crumb rubber, having a higher density (e.g., 1,200
kg/m3), will typically sink to the bottom of the reaction vessel. In cases
where crumb
rubber is used, the bituminous material will be part of a middle layer
interposed
between the polymer layer floating at the surface and the crumb rubber making-
up
the bottom layer.
[0011] Attempts
have been made to mix bitumen with a wide range of
polymers for various applications including roofing and paving. Such polymers
include atactic polypropylene (APP) and styrene block copolymers (SBS) (e.g.,
styrene-butadiene-styrene (SEBS), styrene-isoprene-styrene (SIS), and styrene-
ethylene-butadiene-styrene block copolymers (SEBS)). Unfortunately, it takes a
relatively long time to process or dissolve the above-mentioned polymers in
bituminous materials such as bitumen or various asphalt compositions. Further,
these polymer modifiers can be degraded or aged by heat, UV light, weather or
a
combination thereof.
[0012] Attempts
have also been made to mix rubbers such as ethylene
propylene diene monomer (EPDM) with asphalts. See, e.g., U.S. Pat. Nos.
4,069,181; 4,738,997 and EP Patent Nos. 0338336 Al; 02011671B 1; and 0093500
Al. Additional rubber compositions are described in U.S. Pat. Nos. 3,873,483;
4,129,542; 6,414,056; U.S. Publication Nos. 2006/0243163; 2006/0249049; and
European Application No. EP 0775719 A2. Unfortunately, the mixing often proves
difficult.
[0013] U.S.
5,501,730 claims a process for producing a homogeneous asphalt
composition. While these asphalt compositions may be suitable for various
uses, it
would be beneficial to provide a roofing asphalt composition having a longer
life and
improved weatherability.
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SUMMARY
[0014] The present disclosure broadly relates to an asphalt composition
suitable for roofing applications which is prepared from a paving grade
asphalt. It has
surprisingly been determined that, starting from a paving grade as a roofing
grade
asphalt may be prepared and that such roofing asphalts may include
rubber/elastomer.
[0015] In an aspect, the present disclosure relates to a roofing asphalt
composition comprising an oxidized blend of a paving grade asphalt and
recycled
rubber. In an embodiment, the composition comprises from 60 to 99% by weight
of
the paving grade asphalt; and from 1 to 40% by weight of the recycled rubber.
In yet
a further embodiment, the composition comprises from 80 to 95% by weight of
the
paving grade asphalt; and from 5 to 20% by weight of the recycled rubber.
[0016] In an embodiment, the roofing asphalt composition comprises a
generally uniform mixture of recycled rubber and paving grade asphalt. In yet
a
further embodiment, the recycled rubber and the paving grade asphalt comprise
a
homogenized blend. Though it is understood that the term "homogenize" refers
to a
uniform mixture of elements, as used herein, the term "homogenize" is intended
to
generally refer to a somewhat uniform mixture of components of the roofing
asphalt
composition.
[0017] In an embodiment, the roofing asphalt composition comprises a
recycled rubber comprising at least one of a natural rubber and a synthetic
rubber.
In yet a further embodiment, the recycled rubber is at least partially
vulcanized. In
yet a further embodiment, the recycled rubber is obtained from waste tires or
tubes.
[0018] In an embodiment, at least some of the synthetic rubber selected
from
the group consisting of styrene-butadiene-styrene (SBS), styrene butadiene
(SBR),
styrene-ethylene/butylene-styrene (SEBS), polyethylene, polyisoprene,
polybutylene,
polychloroprene (neoprene), nitrile rubber (acrylonitrile butadiene), butyl
rubber and
polyacrylonitrile.
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[0019] In an
embodiment, the roofing asphalt composition further comprises
from 0.01% to 20% by weight of fluxing oil and optionally from 2% to 8% by
weight of
the fluxing oil.
[0020] In an
embodiment, the roofing asphalt composition further comprises
from 0.01% to 3% by weight of an acid catalyst and optionally from 0.1% to
0.5% by
weight of the acid catalyst.
[0021] In a
further embodiment, the acid catalyst comprises a Lewis acid. In
yet a further embodiment, the acid catalyst is selected from phosphorous
pentoxide,
phosphoric acid, chlorides of zinc, chlorides of iron, chlorides of copper,
chlorides of
antimony, chlorides of aluminum, zinc sulphate, aluminum sulphate, carbonates,
bicarbonate salts of sodium, calcium, magnesium, barium, strontium, lithium,
ammonium, potassium, bismuth, lead,
tetraalkylophosphonium,
tetraarylphosphonium, tetraalkylammonium, trialkylammonium and
dialkylammonium, transition metals, halides of transition metals, rare earth
metals,
boron trifluoride, lead oxide, lead naphthenate and sulphur.
Optionally, the acid
catalyst may be selected from the group consisting of phosphoric acid,
phosphorous
pentoxide, ferric chloride and ferrous chloride. Optionally, the acid catalyst
may
comprise ferrous chloride and/or ferric chloride.
[0022] In an
embodiment, the roofing asphalt composition further comprises a
petroleum fraction. In yet a further embodiment, the petroleum fraction
comprises a
light or medium cycle oil and comprises from 2.0 to 20% by weight of the
composition.
[0023] In an
embodiment, the roofing asphalt composition further comprises
an elastomer. In yet a further embodiment, the elastomer comprises from 0.01
to
5.0% by weight of the composition. Non-limiting examples of elastomers include
styrene-butadiene-styrene (SBS), styrene butadiene (SBR), styrene-
ethylene/butylene-styrene (SEBS), polyethylene, polyisoprene, polybutylene,
polychloroprene (neoprene), nitrile rubber (acrylonitrile butadiene), butyl
rubber and
polyacrylonitrile.
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[0024] In another aspect, the present disclosure relates to a catalytic
process
for preparing a roofing asphalt composition, the process comprising:
(a) catalytically oxidizing a paving grade asphalt and recycled rubber
particles at a temperature ranging from about 2000 to about 300 C and
obtaining a catalytically oxidized mixture;
(b) homogenizing the catalytically oxidized mixture; and
(c) recovering the asphalt composition.
[0025] In an embodiment of the catalytic process, the recycled rubber
particles
have a thickness of up to 1 cm.
[0026] In an embodiment, the catalytic process further comprises adding a
fluxing oil prior to or during the homogenizing step. In a further embodiment
the
fluxing oil is added prior to or during step (a).
[0027] In an embodiment, the catalytic process further comprises selecting
at
least a portion of the recycled rubber from at least one of a natural rubber
and a
synthetic rubber.
[0028] In an embodiment, the catalytic process further comprises selecting
the
recycled rubber from at least partially vulcanized natural rubber and
synthetic rubber.
In an embodiment wherein the process comprises at least partially vulcanized
rubber, the catalytic oxidation is conducted for a time to effect at least a
partial
devulcanization of the rubber.
[0029] In an embodiment, the catalytic process further comprises selecting
at
least a portion of the synthetic rubber from the group consisting of styrene-
butadiene-styrene (SBS), styrene butadiene (SBR), styrene-ethylene/butylene-
styrene (SEBS), polyethylene, polyisoprene, polybutylene, polychloroprene
(neoprene), nitrile rubber (acrylonitrile butadiene), butyl rubber and
polyacrylonitrile.
[0030] In an embodiment, the catalytic process further comprises obtaining
at
least a portion of the recycled rubber from waste tires or tubes.
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[0031] In an
embodiment of the catalytic process, the catalytic oxidation is
conducted in the presence of an acid catalyst. In a further embodiment, the
amount
of acid catalyst ranges from 0.01% to 3% by weight of the composition and
optionally
from 0.05 to 1% by weight of the asphalt composition. In yet a further
embodiment,
the acid catalyst comprises a Lewis acid. In yet a further embodiment, the
acid
catalyst is selected from phosphorous pentoxide, phosphoric acid, chlorides of
zinc,
chlorides of iron, chlorides of copper, chlorides of antimony, chlorides of
aluminum,
zinc sulphate, aluminum sulphate, carbonates, bicarbonate salts of sodium,
calcium,
magnesium, barium, strontium, lithium, ammonium, potassium, bismuth, lead,
tetraalkylophosphonium, tetraarylphosphonium,
tetraalkylammoni um,
trialkylammonium and dialkylammonium, transition metals, halides of transition
metals, rare earth metals, boron trifluoride, lead oxide, lead naphthenate and
sulphur. Optionally, the acid catalyst may be selected from the acid catalyst
from the
group consisting of phosphoric acid, phosphorous pentoxide, ferric chloride
and
ferrous chloride. Optionally, the acid catalyst may be selected from ferrous
chloride
and/or ferric chloride.
[0032] In an
embodiment, the catalytic process further comprises introducing
pressurized air during the catalytic oxidation step. In yet a further
embodiment of the
catalytic process, the catalytic oxidation is conducted at a pressure of from
about 0
(atmospheric pressure) to 50 psig. In yet a further embodiment of the
catalytic
process, the catalytic oxidation is conducted for 1 to 20 hours.
[0033] In an
embodiment, the catalytic process further comprises combining
the paving grade asphalt and the recycled rubber particles at temperatures
ranging
from about 160 C to about 200 C to produce a generally uniform suspension of
the
particles in the asphalt that is subjected to the catalytic oxidation.
[0034] In an
aspect, the present disclosure relates to the use of an asphalt
composition comprising an oxidized blend of a paving grade asphalt and
recycled
rubber for roofing applications. The asphalt composition may be according to
any
one or more of the embodiments disclosed herein.
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[0035] In an
aspect, the present disclosure relates to a roofing product
comprising an asphalt composition comprising an oxidized blend of a paving
grade
asphalt and recycled rubber. The asphalt composition may be according to any
one
or more of the embodiment disclosed herein.
[0036] Other
features and advantages of the present disclosure will become
apparent from the following detailed description. It should be understood,
however,
that the detailed description and the specific examples while indicating
preferred
embodiments of the disclosure are given by way of illustration only, since
various
changes and modifications within the spirit and scope of the disclosure will
become
apparent to those skilled in the art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] The
drawings included herewith are for illustrating various examples of
articles, methods, and apparatuses of the teaching of the present
specification and
are not intended to limit the scope of what is taught in any way.
[0038] FIG. 1
is a schematic drawing of an embodiment of a system suitable
for carrying out the catalytic process of the present disclosure; and,
[0039] FIG. 2
is a schematic drawing of a further embodiment of a system
suitable for carrying out the catalytic process of the present disclosure.
DETAILED DESCRIPTION
I. Glossary
[0040] In order
to provide a clear and consistent understanding of the terms
used in the present specification, a number of definitions are provided below.
Moreover, unless defined otherwise, all technical and scientific terms as used
herein
have the same meaning as commonly understood by one of ordinary skill in the
art
to which this specification pertains.
[0041] The word
"a" or "an" when used in conjunction with the term
"comprising" in the claims and/or the specification may mean "one", but it is
also
consistent with the meaning of "one or more", "at least one", and "one or more
than
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one" unless the content clearly dictates otherwise. Similarly, the word
"another" may
mean at least a second or more unless the content clearly dictates otherwise.
[0042] As used
in this specification and claim(s), the words "comprising" (and
any form of comprising, such as "comprise" and "comprises"), "having" (and any
form of having, such as "have" and "has"), "including" (and any form of
including,
such as "include" and "includes") or "containing" (and any form of containing,
such
as "contain" and "contains"), are inclusive or open-ended and do not exclude
additional, unrecited elements or process steps.
[0043] As used
in this specification and claim(s), the word "consisting" and its
derivatives, are intended to be close ended terms that specify the presence of
stated
features, elements, components, groups, integers, and/or steps, and also
exclude
the presence of other unstated features, elements, components, groups,
integers
and/or steps.
[0044] The term
"consisting essentially of", as used herein, is intended to
specify the presence of the stated features, elements, components, groups,
integers,
and/or steps as well as those that do not materially affect the basic and
novel
characteristic(s) of features, elements, components, groups, integers, and/or
steps.
[0045] The
terms "about", "substantially" and "approximately" as used herein
mean a reasonable amount of deviation of the modified term such that the end
result
is not significantly changed. These terms of degree should be construed as
including a deviation of at least 1% of the modified term if this deviation
would not
negate the meaning of the word it modifies.
[0046] The term
"suitable" as used herein means that the selection of the
particular material or conditions would depend on the specific synthetic
manipulation
to be performed, and the identity of the material(s) to be transformed, but
the
selection would be well within the skill of a person trained in the art.
All
process/method steps described herein are to be conducted under conditions
sufficient to provide the product shown. A person skilled in the art would
understand
that all reaction conditions, including, for example, reaction time, reaction
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temperature, reaction pressure and reactant ratio, can be varied to optimize
the yield
of the desired product and it is within their skill to do so.
[0047] The expression "proceed to a sufficient extent" as used herein with
reference to the reactions or process steps disclosed herein means that the
reactions or process steps proceed to an extent such that conversion of the
starting
material or substrate to product is maximized. Conversion may be maximized
when
greater than about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75,
80, 85,
90, 95 or 99% of the starting material or substrate is converted to product.
[0048] The term "composition" as used herein, includes a mixture of
materials
which comprise the composition, as well as reaction products and decomposition
products formed from the materials of the composition.
[0049] The term "waterproofing" as used herein, refers to the process of
making a building component (e.g. a roofing component) resistant to the
passage of
water and/or water vapor.
[0050] Further, the definitions and embodiments described in particular
sections are intended to be applicable to other embodiments herein described
for
which they are suitable as would be understood by a person skilled in the art.
For
example, in the following passages, different aspects of the invention are
defined in
more detail. Each aspect and embodiment so defined may be combined with any
other aspect or aspects or embodiment or embodiments unless clearly indicated
to
the contrary. In particular, any feature indicated as being preferred or
advantageous
may be combined with any other feature or features indicated as being
preferred or
advantageous.
[0051] In an embodiment, the present disclosure relates to a roofing
asphalt
composition that is characterized by significantly improved weatherability
characteristics. The roofing asphalt compositions of the present disclosure
comprise
an oxidized blend of a paving grade asphalt and recycled rubber. In an
embodiment,
the recycled rubber comprises at least one of a natural rubber and a synthetic
rubber. In a further embodiment, at least a portion of the recycled rubber is
at least
CA 02862303 2014-09-05
partially vulcanized. In yet a further embodiment, at least some of the
recycled
rubber is obtained from waste tires or tubes. In particular embodiments of the
present disclosure, at least some of the synthetic rubber is selected from the
group
consisting of styrene-butadiene-styrene (SBS), styrene butadiene (SBR),
styrene-
ethylene/butylene-styrene (SEBS), polyethylene, polyisoprene, polybutylene,
polychloroprene (neoprene), nitrile rubber (acrylonitrile butadiene), butyl
rubber and
polyacrylonitrile. The amount and ratio of paving grade asphalt and recycled
rubber
will depend on the desired physical and mechanical properties of the final
asphalt
composition.
[0052] In an aspect, the roofing asphalt compositions of the present
disclosure
exhibit improved temperature and UV stabilities. In further embodiments, the
roofing
asphalt compositions disclosed herein exhibit improved weatherability. In yet
a
further aspect, the use of recycled rubber reduces manufacturing costs.
[0053] In an aspect, the present disclosure relates to methods of using
the
compositions in various roofing applications such as but not limited to
waterproofing
shingles, sheets or membranes for roofs.
[0054] In an aspect, the present disclosure relates to articles comprising
at
least one component formed from the compositions disclosed herein.
Methods for Preparing Roofing Asphalt Compositions
[0055] In one of its embodiments, the present disclosure includes a
catalytic
process for preparing a roofing asphalt composition, the process comprising:
(a) optionally combining paving grade asphalt and recycled rubber
particles at temperatures ranging from about 160 C to about 200 C to
produce a generally uniform suspension of the particles in the asphalt;
(b) catalytically oxidizing the suspension at a temperature ranging from
about 2000 to about 300 C and obtaining a catalytically oxidized mixture;
(c) homogenizing the catalytically oxidized mixture; and,
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(d) recovering the asphalt composition.
[0056] The process may be conducted using any equipment known in the art.
FIG. 1 illustrates a schematic of an embodiment, referred to as system 10,
suitable
for the catalytic preparation of the roofing asphalt composition of the
present
disclosure. As exemplified, paving grade asphalt and recycled rubber particles
are
combined in a reactor, such as stirred tank or mixer 12. The paving grade
asphalt
and recycled rubber particles may be added concurrently or sequentially in any
order
and may be added by the same stream or different streams. For example, as
exemplified, recycled rubber particles are introduced into mixer 12 from,
e.g.,
dispenser 14 via conveyor 16, while asphalt (bitumen) is introduced into the
mixer
from tank 15 via pipe 18.
[0057] The paving grade asphalt may be any asphalt (as defined in ASTM D-
1079) or mixture thereof that would have a PEN (ASTM D-5) greater than 40 dmm,
or that would have a viscosity (ASTM D-2171) of less than 500 Pa.S (Pascal-
seconds) at 60 C [140 F]. In an embodiment of the present disclosure, the
paving
grade asphalt may comprise, consist essentially of or consist of one or more
paving
grade asphalts having a PEN (ASTM D-5) falling within the Penetration Graded
Asphalt cement of ASTM D-946; one or more paving grade asphalts (as defined in
ASTM 0-1079) that have a viscosity (ASTM 0-2171) falling within the Viscosity
Graded asphalt cement of ASTM 0-3381; and/or one or more paving grade asphalts
(as defined in ASTM D-1079) that would have a Dynamic Shear, G*/sin 6 value
[determined by either ASTM-7175 or AASHTO T-315] above 1.00 kilopascal at any
temperature above 46 C. In a further embodiment of the present disclosure, the
paving grade asphalt may comprise, consist essentially of or consist of one or
more
paving grade asphalts that meet one of the paving asphalt grades 150/200 PEN,
85/100 PEN, 60/70 PEN, AC-10, AC-20, AC-30, PG58-28, PG64-22 and PG67-22.
[0058] The final roofing asphalt may comprise from 60 to 99% by weight of
the
paving grade asphalt. In non-limiting embodiments, for example, the paving
grade
asphalt may comprise, for example, 60, 65, 70, 75, 80, 85, 90, 95 or 99 % by
weight
of the roofing asphalt composition, or any range or integer derivable therein
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[0059] The recycled rubber particles may be any rubber material covered
under either ASTM D-5603 or ASTM D-6114. The final roofing asphalt may
comprise from 1 to 40% by weight of the recycled rubber particles. In non-
limiting
embodiments, for example, the recycled rubber particles may comprise, for
example,
1, 5, 10, 15, 20, 25, 30, 35 or 40% by weight of the roofing asphalt
composition, or
any range or integer derivable therein.
[0060] Mixer 12 may be operated so as to produce a generally uniform
mixture. For example, the paving grade asphalt and recycled rubber particles
may be
mixed at an elevated temperature for a sufficient amount of time to generally
uniformly distribute the recycled rubber particles in the paving grade
asphalt. It will
be appreciated that the amount of time will vary depending, inter alia, upon
the
starting temperature of the paving grade asphalt and recycled rubber particles
prior
to their introduction to mixer 12, the temperature of the mixture in mixer 12,
the
degree of agitation that is provided (e.g., the rpm of a stirrer 12b in mixer
12 and the
size of the recycled rubber particles introduced to mixer 12.
[0061] Optionally, the temperature of the mixture in mixer 12 is maintained
at
about 160 C to about 200 C and the mixture remains therein under agitation
until the
rubber particles are generally uniformly suspended in the asphalt. For
example, the
mixture may be agitated in mixer 12 for a period of time varying, e.g., from
30
minutes to 3 hours, at a temperature of, e.g., 160 -180 C, depending on the
starting materials and the properties required for the asphalt composition.
[0062] The resulting suspension may then be catalytically oxidized.
Accordingly, the resulting suspension may be transferred directly to a reactor
24.
However, if the resulting suspension is not at a desired temperature for
introduction
to reactor 24, it may be subjected to additional heating prior to introduction
to reactor
24, and/or stored, e.g., in a holding tank (not shown).
[0063] The use of mixer 12 results in the "wetting" of the rubber in
preparation
for introduction into reactor 24. As the rubber particles are mixed in the
asphalt, the
rubber particles commence exuding oils that can lower the flash point. A lower
flash
point may result in unsafe conditions being present for the catalytic
oxidation step.
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Using mixer 12 enables these oils to be exuded and removed if needed to
prevent
excessive lowering of the flash point. If the flash point is not a concern,
then the
combining step may be omitted. In such a case, the components may be added
directly to reactor 24.
[0064] As exemplified in Fig. 1, the resulting suspension is transferred
via
pipe 22 into heat exchanger 20, wherein the temperature may be further raised,
e.g.,
to about 230 C. Heat exchanger 20 may be an indirect heat exchanger and may
operate counter currently using waste heat, e.g., in the form of a heated
fluid stream,
such as tail gas or wet steam, that is available at the site.
[0065] The suspension is subsequently transferred into a reactor 24 where
it
is catalytically oxidized. The catalytic oxidation may be conducted at an
elevated
temperature and/or pressure for a sufficient amount of time to produce an
asphalt
composition meeting the specification for a selected roofing grade asphalt. It
will be
appreciated by a person skilled in the art that the catalytic oxidation may
occur in
one step or more than one step.
[0066] The rubber employed in the manufacture of tires and tubes is
typically
vulcanized, that is, the polymer chains are crosslinked by sulfur bridges,
with the
result that the physical properties of the rubber material thus treated are
improved
while its elasticity is maintained. To be suitable for the purposes of the
present
invention, such waste rubber is treated to be at least partially devulcanized.
In an
embodiment of the present disclosure, devulcanization is accomplished by
catalytic
oxidation at an elevated temperature and pressure.
[0067] The catalytic oxidation may be conducted over a period of time
ranging
from 1 to 20 hours. The oxidation times will vary based on the nature of the
paving
grade asphalt and recycled rubber introduced into the reactor, the degree of
devulcanization of the rubber, the selected grade of the roofing asphalt that
is to be
produced and the pressure and temperature at which the catalytic oxidation is
conducted. A second reactor 36, in fluid communication with the first reactor
24,
may be incorporated into the catalytic process where longer oxidation periods
are
required (see system 11 in Fig. 2). In such a case, the asphalt may be
catalytically
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oxidized to a first degree in first reactor 24 and may be further
catalytically oxidized
in second reactor 36. An advantage of system 11 resides in the fact that
larger
volumes of asphalt composition can be produced over a given period of time. In
non-limiting embodiments, for example, the catalytic oxidation may be
performed, for
example, for at least 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7
hours, 8
hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16
hours, 17 hours, 18 hours, 19 hour or 20 hours or any range or integer
derivable
therein.
[0068] The catalyst and oxygen may be introduced into reactor 24 by any
means known in the catalytic oxidation arts. As exemplified, reactor 24 is
equipped
separate inlets for the introduction of the catalyst and oxygen. Inlet 17 is
provided for
the introduction of the catalyst and inlet 19 is provided for the injection of
a
pressurized oxygen containing gas, such as air, oxygenated air or oxygen.
Inlets 17
and 19 may be located at any location on reactor 24. Optionally, the
pressurized
oxygen containing gas is advantageously injected through an inlet located near
the
bottom of reactor 24 to maximize mixing of the pressurized air with the
suspension.
In an alternate embodiment of the present disclosure, the catalyst and the
pressurized gas may be introduced into reactor 24 through the same inlet.
[0069] Reactor 24 may be operated at temperatures ranging from about
200 C to about 300 C, optionally 210 C to 290 C, optionally 220 C to 280 C,
and
optionally 230 C to 260 C. The oxidation temperatures will vary based on the
nature
of the paving grade asphalt and recycled rubber introduced into the reactor,
the
degree of devulcanization of the rubber, the selected grade of the roofing
asphalt
that is to be produced, the pressure at which the catalytic oxidation is
conducted and
the duration of the catalytic oxidation process. In non-limiting embodiments,
for
example, the catalytic oxidation may be performed, for example, at a
temperature of
205 C, 210 C, 215 C, 220 C, 225 C, 230 C, 235 C, 240 C, 245 C, 250 C, 255 C,
260 C, 265 C, 270 C, 275 C, 280 C, 285 C, 290 C, 295 C or 300 C or any range
or
integer derivable therein.
CA 02862303 2015-07-14
[0070] Reactor
24 may be operated at pressures ranging from 0 to 50 psig. It
is to be noted that the pressure could be higher depending on the height of
reactor
24. In non-limiting embodiments, for example, the catalytic oxidation may be
performed, for example, at pressures ranging from 5 to 40 psig or 5 to 30
psig. The
oxidation pressures will vary based on the nature of the paving grade asphalt
and
recycled rubber introduced into the reactor, the degree of devulcanization of
the
rubber, the selected grade of the roofing asphalt that is to be produced, the
temperature at which the catalytic oxidation is conducted and the duration of
the
catalytic oxidation process. In non-limiting embodiments, for example, the
catalytic
oxidation may be performed, for example, at a pressure of 10, 15, 20, 25, 30,
35, 40,
45 or 50 psig or any range or integer derivable therein.
[0071] The
catalyst may be an acid catalyst. The amount of acid catalyst may
range from 0.01% to 3% dry catalyst based on the total weight of the
composition. In
non-limiting embodiments, for example, the amount of catalyst may be at least
about
0.0150%, 0.0200%, 0.0225%, 0.0250%, 0.0275%, 0.0300%, 0.0325%, 0.0350%,
0.0375%, 0.0400%, 0.0425%, 0.0450%, 0.0475%, 0.0550%, 0.0575%, 0.0600%,
0.0625%, 0.0650%, 0.0675%, 0.0700%, 0.0725%, 0.0750%, 0.0775%, 0.0800%,
0.0825%, 0.0850%, 0.0875%, 0.0900%, 0.0925%, 0.0950%, 0.0975%, 0.1000%,
0.1250%, 0.1500%, 0.1750%, 0.2000%, 0.2250%, 0.2500%, 0.2750%, 0.3000%,
0.3250%, 0.3500%, 0.3750%, 0.4000%, 0.4250%, 0.4500%, 0.4750%, 0.5000%,
0.5250%, 0.550%, 0.5750%, 0.6000%, 0.6250%, 0.6500%, 0.6750%, 0.7000%,
0.7250%, 0.7500%, 0.7750%, 0.8000%, 0.8250%, 0.8500%, 0.8750%, 0.9000%,
0.9250%, 0.9500%, 0.9750%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%,
1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9% or 3.0%
or any range or integer derivable therein.
[0072] The
catalyst may be any of those disclosed in U.S. Pat. Nos. 1,782,186,
2,450,756, 2,375,117 and 2,649,584. Further, the catalyst may be one of those
disclosed in European Patent Publication Number EP0053041.
16
CA 02862303 2014-09-05
[0073] The acid
catalyst may comprise, consist essentially of or consist of a
Lewis acid.
[0074] The acid
catalyst may be selected from phosphorous pentoxide,
phosphoric acid, chlorides of zinc, chlorides of iron, chlorides of copper,
chlorides of
antimony, chlorides of aluminum, zinc sulphate, aluminum sulphate, carbonates,
bicarbonate salts of sodium, calcium, magnesium, barium, strontium, lithium,
ammonium, potassium, bismuth, lead,
tetraalkylophosphonium,
tetraarylphosphonium, tetraalkylammonium, trialkylammonium and
dialkylammonium, transition metals, halides of transition metals, rare earth
metals,
boron trifluoride, lead oxide, lead naphthenate, sulphur and mixtures thereof.
[0075]
Alternately, the acid catalyst may be selected from the group consisting
of phosphoric acid, phosphorous pentoxide, ferric chloride, ferrous chloride
and
mixtures thereof.
[0076]
Alternately, the acid catalyst may comprise, consist essentially of or
consist of ferrous chloride, ferric chloride and mixtures thereof.
[0077] The
catalytic oxidation will produce a tail gas. The tail gas may be
recycled in whole or in part and/or it may be released into the atmosphere.
Optionally, the tail gas is conveyed by a pipe 25, to a tail gas treatment
unit wherein
the tail gas may be cleaned or purified, e.g., by air filter or purifier 26
before being
released into the atmosphere.
[0078] The
oxidized mixture may then be homogenized using any means
known in the art or it may be stored prior to being homogenized.
Homogenization
provides stability of the composition during extended periods of storage. As
exemplified, the oxidized mixture is transferred into dispersing device 28
through
pipe 30, to homogenize the oxidized mixture. The dispersing device 28 may
comprise a pair of mating toothed discs turning at a speed of, e.g., about
3600 RPM.
Operation of a homogenizer at such high speeds assist in continued catalytic
oxidation of the composition. In an alternate embodiment of the present
disclosure,
the oxidized mixture is homogenized using a high shear mixer or mill.
17
CA 02862303 2014-09-05
[0079] The
homogenized mixture may optionally be subjected to a static mixer
32 (e.g., by being conveyed through a static mixer). The static mixer further
enhances the degree of homogenization produced by dispersing device 28.
[0080] The
homogenized mixture may then be used or stored until required.
As exemplified, the homogenized mixture is conveyed from static mixer to
storage
container 34. The storage temperature in container 34 typically ranges from
about
170 C to about 260 C.
[0081] System
10 and the associated catalytic process provides for an asphalt
composition suitable for roofing applications. Various adjustments of the
operational
conditions (e.g. temperature, pressure, time in the reactor, ratio of
ingredients etc.),
to obtain the desired physical properties/characteristics of the roofing
asphalt, may
be selected by a person of skill in the art.
[0082] A
fluxing oil may be added during the process, such as prior to or during
the step of combining the paving grade asphalt and recycled rubber particles
(e.g.,
fluxing oil may be added by a separate stream into mixer 12 and/or fluxing oil
may be
added to one or both of the paving asphalt and rubber particles prior to their
introduction to mixer 12), during the step of homogenizing the catalytically
oxidized
mixture (e.g., fluxing oil may be added to dispersing device 28 and/or static
mixer 32)
and/or by adding fluxing oil to the catalytically oxidized mixture and prior
to
homogenizing the catalytically oxidized mixture (e.g., fluxing oil may be
added to the
catalytically oxidized asphalt prior to introduction to dispersing device 28
and/or
static mixer 32). The fluxing oil may be a light or medium cycle oil obtained
from the
distillation of oil. The fluxing oil may be a re-refined heavy vacuum
distillation bottom
The fluxing oil is utilized to adjust the consistency of the asphalt and the
amount
which is added may be adjusted to produce a desired grade of roofing asphalt.
The
fluxing oil may comprise from 0.01% to 20%, 2% to 8% by weight of the asphalt
composition. In non-
limiting embodiments, for example, the fluxing oil may
comprise, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
17, 18, 19
or 20 % by weight of the asphalt composition, or any range or integer
derivable
therein.
18
CA 02862303 2014-09-05
[0083] Polymeric elastomers, non-limiting examples of which include
styrene-
butadiene-styrene (SBS), styrene butadiene (SBR), styrene-ethylene/butylene-
styrene (SEBS), polyethylene, polyisoprene, polybutylene, polychloroprene
(neoprene), nitrile rubber (acrylonitrile butadiene), butyl rubber and
polyacrylonitrile
may be added to improve the elongation properties and elasticity of the final
asphalt
compositions. The amount of elastomer may range from about 0.01 to about 5.0%
by weight of the composition and depends on the desired physical and
mechanical
properties of the roofing asphalt.
[0084] The resulting roofing asphalt may be any roofing asphalt (as
defined in
ASTM D-1079) that would have a softening point (ASTM D-36) higher than 50 C
and
PEN at 25 C (ASTM D-5) between 5 and 70 dmm. In an alternate embodiment of
the present disclosure, the resulting roofing asphalt may be any roofing
asphalt (as
defined in ASTM D-1079) that would have a softening point (ASTM D-36) higher
than 80 C and PEN at 25 C (ASTM D-5) between 5 and 40 dmm. In an alternate
embodiment of the present disclosure, the resulting roofing asphalt may be any
roofing asphalt (as defined in ASTM D-1079) that would fall within the
Standard
Specification for Asphalt Used in Roofing (ASTM D-312).
[0085] The catalytic process of the present disclosure is both efficient
and
economical as it relies on recycled rubber as one of its ingredients.
Moreover, the
relatively short reaction times result in a very limited production of
degradation
products further ensuring the quality of the final asphalt composition.
Furthermore,
the catalytic process of the present disclosure may result in reduced levels
of liquid
or solid wastes making it suitable to large scale production.
[0086] It will be appreciated that standard additives, such as a UV
stabilizer,
may be added to the roofing asphalt.
[0087] The rheological and mechanical properties of the asphalt
compositions
of the present disclosure, as referred to in the examples, and more
particularly in
Table 1 are as follows:
19
CA 02862303 2014-09-05
[0088] PEN: penetration is measured by the standardized procedure ASTM-
D5; Softening Points are measured by the ring and ball method ASTM-D36;
Viscosity is measured using ASTM 04402; Accelerated aging using a Weather-0-
meter is measured according to ASTM D4798; Flash Points are measured by ASTM
092; Storage Stabilities are measured using ASTM D7173; Elasticity, Resilience
and
Ductility tests were performed under the current standard methods fixed by the
ASTM Committee; and Stain Indexes are measured by standardized procedure
ASTM D2746.
[0089] A number of representative non-limiting examples are provided
herein
below illustrating the preparation of various roofing asphalt compositions in
accordance with the present disclosure. It should be noted that the expression
"crumb rubber" cited in the examples, refers to rubber obtained from waste
tires or
tubes.
EXAMPLE 1: Samples S00531, S00532, S00533 and S00535
[0090] A mixture of asphalt PG 64-22 or an equivalent (2550 g) and crumb
rubber from recycled passenger tires (450 g - 30 mesh) is heated to 200-260 C
under pressurized air in a reactor equipped with a mechanical mixer. After 4
hours,
the resulting mixture is removed from the reactor and any residual crumb
rubber is
further reduced using a high shear mixer. Selected physical properties of the
resulting asphalt compositions are illustrated in Table 1.
EXAMPLE 2: Samples S00608, S00609, S00610 and S00611
[0091] A mixture of asphalt PG 64-22 (2239.5 g), crumb rubber from
recycled
passenger tires (450 g - 30 mesh), a fluxing oil, namely asphalt extender from
re-
refined heavy vacuum distillation bottoms (300 g) and ferrous chloride (10.5
g) is
heated to 200-260 C under pressurized air in a reactor equipped with a
mechanical
mixer. After 3 hours, the resulting mixture is removed from the reactor
without
subsequent homogenization. Selected physical properties of the resulting
asphalt
compositions are also illustrated in Table 1.
CA 02862303 2015-07-14
[0092] A coating sample was subjected to accelerated weathering in Atlas
Weather-O-meter 014000 according to ASTM D 4798, cycle A.
[0093] Samples S00531, S00532, S00533, S00535, 500537 and S00643 are
comparative examples that were run without a catalyst. As set out in Table 1,
samples S00531, S00532, S00533, S00535, S00537 and S00643 illustrate that, in
absence of a catalyst, regardless of the source of the paving asphalt, the
oxidized
composition had a penetration less than 15 dmm for PEN, even before the
softening
point reached 100 C.
[0094] Samples S00655 and S00657 illustrate that catalytic oxidation of an
appropriate paving grade asphalt may produce a roofing asphalt with acceptable
PEN results. However, in the absence of crumb rubber, the weatherability
results
are poor.
[0095] Samples S00608, S00609, S00610, S00611 and S00644 illustrate that
the presence of both catalyst and crumb rubber result in the production of a
roofing
asphalt exhibiting good characteristics.
[0096] It should be noted that the presence of a filler is not required and
was
merely used to qualify the weathering test.
[0097] While the present disclosure has been described with reference to
what are presently considered to be the preferred examples, it is to be
understood
that the disclosure is not limited to the disclosed examples. In particular,
what has
been described herein has been intended to be illustrative and non-limiting
and it will
be understood by persons skilled in the art that other variants and
modifications may
be made without departing from the scope of the invention as defined in the
claims
appended hereto. The scope of the claims should not be limited by the
preferred
embodiments and examples, but should be given the broadest interpretation
consistent with the description as a whole.be
21
Table 1: Selected Physical Properties for Various Roofing Asphalt Compositions
in Accordance with Various Embodiments of
the Present Disclosure.
CODE Oxidation Date TBA Pen Paving Grade SupplierFluxing Oil Crumb
Rubber Catalyst Filler weathering Comments
Source
500531 June 8, 2011 93.5 10.3 85% PG64-22 "A"
None 15% of 30 mesh None 69% 2000 Failed PEN <15
_
500532 June 9, 2011 93.0 8.7 85% PG64-22 "B" None
15% of 30 mesh None _ 69% 2000 Failed PEN < 15
_
500533 June 10, 2011 96.0 6.7 85% PG64-22 "C" None
15% of 30 mesh None 69% _ 2000 Failed PEN <15
_
500535 June 14, 2011 107.0 6.0 85% PG64-22 "C" None
15% of 30 mesh None 69% _ 2000 Failed PEN < 15
500537 June 21, 2011 96.0 8.3 85% PG64-22 "D" None
15% of 30 mesh None 69% _ 2000 Failed PEN <15
500608 May 24, 2012 100.0 22.7 74.65% PG64-22
"D" 110% RHVDB 15% of 30 mesh 0.35% FeCl2 69% _ 4000 Excellent
a
500609 May 28, 2012 98.0 23.7 , 74.65% PG64-22
"A" I 10% RHVDB 15% of 30 mesh 0.35% FeCl2 69% _ 2800 Acceptable
o
500610 May 29, 2012 103.5 21.7 74.65% PG64-22
"B" 10% RHVDB 15% of 30 mesh 0.35% FeCl2 69% _ 5600 Excellent
n)
co
500611 May 31, 2012 93.5 31.0 I 74.65% PG64-22 "E" 10%
RHVDB 15% of 30 mesh 0.35% FeCl2 69%_ 4000 _ Excellent cl)
n)
500643 April 25, 2013 108.5 4.7 80% PG64-22 "A" 10% RHVDB 10% of
30 mesh None 69% 4000 Failed PEN <15 w
_
o
500644 April 29, 2013 100.0 16.0 179.65% PG64-22_ "A"
10% RHVDB 10% of 30 mesh 0.35% FeCl2 69% 2800 Acceptable w
n)
500655 May 22, 2013 100.0 16.0 67.25% PG64-22 "A" 10% RHVDB
None 0.35% FeCl2 69% 1600 Poor o
I 22.4% 150/200 "F"_ Weatherability
67.25%
r'- '2 "A"
Poor 01
500657 May 23, 2013 95.5 17.0 10% RHVDB None 0.35%
FeCl2 69% 1200
22.4% Flux "G"
I Weatherability -..]
i
1-.
.D.
22
