U.S. patent application number 16/123749 was filed with the patent office on 2019-08-08 for system and method for high throughput preparation of rubber-modified asphalt cement.
The applicant listed for this patent is Wright Asphalt Products Company. Invention is credited to Theodore P. Flanigan.
Application Number | 20190241742 16/123749 |
Document ID | / |
Family ID | 42060020 |
Filed Date | 2019-08-08 |
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United States Patent
Application |
20190241742 |
Kind Code |
A1 |
Flanigan; Theodore P. |
August 8, 2019 |
System and Method for High Throughput Preparation of
Rubber-Modified Asphalt Cement
Abstract
This invention encompasses rubber modified asphalt cement
compositions, as well as systems, apparatuses, methods for
preparing, as well as methods for using rubber-modified asphalt
cement compositions.
Inventors: |
Flanigan; Theodore P.;
(League City, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Wright Asphalt Products Company |
Houston |
TX |
US |
|
|
Family ID: |
42060020 |
Appl. No.: |
16/123749 |
Filed: |
September 6, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15716181 |
Sep 26, 2017 |
10093804 |
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16123749 |
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15370754 |
Dec 6, 2016 |
9803085 |
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15716181 |
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14598965 |
Jan 16, 2015 |
9540512 |
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15370754 |
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14036956 |
Sep 25, 2013 |
8969442 |
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14598965 |
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13493557 |
Jun 11, 2012 |
8664304 |
|
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14036956 |
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12733706 |
Mar 16, 2010 |
8202923 |
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PCT/US2009/005295 |
Sep 24, 2009 |
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13493557 |
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61136677 |
Sep 24, 2008 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08L 19/003 20130101;
C08L 2555/34 20130101; C08L 2555/86 20130101; C08L 2666/08
20130101; C08J 2395/00 20130101; C08L 95/00 20130101; C08J 3/005
20130101; C08L 2555/22 20130101; C08L 95/00 20130101; C08L 21/00
20130101; C08L 95/00 20130101; C08L 95/00 20130101; C08L 2666/08
20130101; C08L 21/00 20130101; B28C 7/003 20130101; C09D 195/00
20130101; C08L 21/00 20130101 |
International
Class: |
C08L 95/00 20060101
C08L095/00; B28C 7/00 20060101 B28C007/00; C09D 195/00 20060101
C09D195/00; C08J 3/00 20060101 C08J003/00; C08L 21/00 20060101
C08L021/00 |
Claims
1. A method for preparing a rubber-modified asphalt cement
composition, comprising: i) contacting asphalt with rubber granules
to form a mixture; ii) heating the mixture to a temperature in the
range of 450.degree. F. to 510.degree. F. to form a heated mixture;
iii) mixing at least a portion of the heated mixture with rubber
granules in a pre-wet vessel comprising a mixer to form a heated
wetted asphalt/rubber mixture; and iv) passing the heated wetted
asphalt/rubber mixture through at least one high shear mixer,
wherein the rubber-modified asphalt cement composition has an
integration value of at least 90.
2. The method of claim 1, wherein the temperature is in the range
of 460.degree. F. to 510.degree. F.
3. The method of claim 1, wherein the temperature is in the range
of 480.degree. F. to 510.degree. F.
4. The method of claim 1, wherein the temperature is in the range
of 490.degree. F. to 510.degree. F.
5. The method of claim 1, wherein the rubber-modified asphalt
cement composition has a rubber content in the range of 5-35 wt. %
relative to the total weight of the rubber-modified asphalt cement
composition.
6. The method of claim 1, wherein the rubber-modified asphalt
cement composition has a rubber content in the range of 5-15 wt. %
relative to the total weight of the rubber-modified asphalt cement
composition.
7. The method of claim 1, wherein the rubber-modified asphalt
cement composition has a rubber content of greater than 18 wt. %
relative to the total weight of the rubber-modified asphalt cement
composition.
8. The method of claim 1, wherein the rubber-modified asphalt
cement composition is an rubber-modified asphalt cement
concentrate.
9. An rubber-modified asphalt cement composition, prepared by: i)
contacting asphalt with rubber granules to form a mixture; ii)
heating the mixture to a temperature in the range of 450.degree. F.
to 510.degree. F. to form a heated mixture; iii) mixing at least a
portion of the heated mixture with rubber granules in a pre-wet
vessel comprising a mixer to form a heated wetted asphalt/rubber
mixture; and iv) passing the heated wetted asphalt/rubber mixture
through at least one high shear mixer, wherein the rubber-modified
asphalt cement composition has an integration value of at least
95.
10. The rubber-modified asphalt cement composition of claim 9,
wherein the temperature is in the range of 460.degree. F. to
510.degree. F.
11. The rubber-modified asphalt cement composition of claim herein
the temperature is in the range of 480.degree. F. to 510.degree.
F.
12. The rubber-modified asphalt cement composition of claim 9,
wherein the temperature is in the range of 490.degree. F. to
510.degree. F.
13. The rubber-modified asphalt cement composition of claim 9,
wherein the rubber-modified asphalt cement composition has a rubber
content in the range of 5-35 wt. % relative to the total weight of
the rubber-modified asphalt cement composition.
14. The rubber-modified asphalt cement composition of claim 9,
wherein the rubber-modified asphalt cement composition has a rubber
content in the range of 5-15 wt. % relative to the total weight of
the rubber-modified asphalt cement composition.
15. The rubber-modified asphalt cement composition of claim 9,
wherein the rubber-modified asphalt cement composition has a rubber
content of greater than 18 wt. % relative to the total weight of
the rubber-modified asphalt cement composition.
16. A system for preparing an rubber-modified asphalt cement
composition, comprising: i) an asphalt charging device for charging
asphalt into the system; ii) a rubber charging device for charging
rubber granules into the system; iii) at least one heater for
heating the charged asphalt, the charged rubber granules, or a
mixture thereof to a temperature in the range of 450.degree. F. to
510.degree. F.; iv) at least one pre-wet vessel comprising a mixer
to form a wetted asphalt/rubber mixture from the charged asphalt
and charged rubber granules; v) at least one high shear mixer for
mixing the wetted asphalt/rubber mixture into the rubber-modified
asphalt cement composition; and vi) a controller for controlling
the asphalt charging device, the rubber charging device, and/or the
at least one high shear mixer, in a manner such that the
rubber-modified asphalt cement composition has an integration value
of at least 95.
17. The system of claim 16, wherein the temperature is in the range
of 460.degree. F. to 510.degree. F.
18. The system of claim 16, wherein the temperature is in the range
of 480.degree. F. to 510.degree. F.
19. The system of claim 16, wherein the temperature is in the range
of 490.degree. F. to 510.degree. F.
20. The system of claim 16, wherein the rubber-modified asphalt
cement composition comprises 5-15 wt. % rubber.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/716,181, filed Sep. 26. 2017, which is
further a continuation of U.S. patent application Ser. No.
15/370,754, filed Dec. 6, 2016, now U.S. Pat. No. 9,803,085, which
is further a continuation of U.S. patent application Ser. No.
14/598,965, filed Jan. 16, 2015, now U.S. Pat. No. 9,540,512, which
is a continuation of U.S. patent application Ser. No. 14/036,956,
filed Sep. 25, 2013, now U.S. Pat. No. 8,969,442, which is a
continuation of U.S. patent application Ser. No. 13/493,557, filed
Jun. 11, 2012, now U.S. Pat. No. 8,664,304, which is further a
continuation of U.S. patent application Ser. No. 12/733,706, filed
Mar. 16, 2010, now U.S. Pat. No. 8,202,923, which is the National
Stage of International Application No. PCT/US2009/005295, filed
Sep. 24, 2009, which designated the United States and published in
English, and which further claims the benefit of priority from U.S.
Provisional Application No. 61/136,677, filed Sep. 24, 2008.
Priority to each of the foregoing applications is expressly
claimed, and the disclosures of each of the respective foregoing
applications are hereby incorporated by reference in their
entireties for all purposes.
FIELD OF THE INVENTION
[0002] This invention relates to a rubber-modified asphalt cement,
and to systems, apparatuses, and methods for preparing a
rubber-modified asphalt cement.
BACKGROUND OF THE INVENTION
[0003] Several attempts have been made to produce rubber-modified
asphalt cements having the highly desirable properties of stability
and prolonged high-level resistance to water-, fuel-, and
ultraviolet (UV) light-associated degradation.
[0004] Specifically, for example, U.S. Pat. Nos. 5,397,818,
5,492,561 (Flanigan I) and U.S. Pat. No. 5,583,168 (Flanigan II)
describe processes for liquefying rubber granules in a TRMACS
process, by heating crumb rubber and asphalt to temperatures of
approximately 500.degree. F. using spray jets or spray
bombardment.
[0005] Although several achievements have been made in producing
asphalt cements having desirable properties, a need still remain
for improved rubber-modified asphalt cement that possess superior
stability and shielding properties, and for systems, apparatuses,
and methods for high throughput production of such rubber-modified
asphalt cements.
[0006] The present invention provides such an improved asphalt
cement, as well as systems and methods for preparing and using such
a rubber-modified asphalt cement.
BRIEF SUMMARY OF THE INVENTION
[0007] In one aspect, the present invention relates to a method for
preparing a rubber-modified asphalt cement composition, comprising:
contacting asphalt with rubber granules to form a mixture; heating
the mixture; and passing the heated mixture through at least one
high shear mixer; wherein the rubber-modified asphalt cement
composition comprises an integration value of at least 90. In
another aspect, the present invention relates to a method for
preparing a rubber-modified asphalt cement composition, comprising:
contacting asphalt with rubber granules to form a mixture; heating
the mixture to a temperature of at least about 500.degree. F.; and
passing the heated mixture through at least one high shear mixer
for greater than 30 minutes.
[0008] In another aspect, the present invention relates to a method
for high throughput preparation of a rubber-modified asphalt cement
composition, comprising: contacting asphalt with at least 40,000
pounds of rubber granules to form a mixture; heating the mixture;
and passing the heated mixture through at least one high shear
mixer; wherein the rubber-modified asphalt cement composition
comprises an integration value of at least 90, and wherein the
method is performed in less than 24 hours.
[0009] In another aspect, the present invention relates to a
rubber-modified asphalt cement composition prepared by: contacting
asphalt with rubber granules to form a mixture; heating the
mixture; and passing the heated mixture through at least one high
shear mixer; wherein the rubber-modified asphalt cement composition
comprises an integration value of at least 90.
[0010] In another aspect, the present invention relates to a system
for preparing a rubber-modified asphalt cement composition,
comprising: an asphalt charging device for charging asphalt into
the system; a rubber charging device for charging rubber granules
into the system; at least one heater for heating the charged
asphalt, the charged rubber granules, or a mixture thereof; at
least one high shear mixer for mixing the charged asphalt and
charged rubber granules into a rubber-modified asphalt cement
composition; and a controller for controlling the asphalt charging
device, the rubber charging device, and/or the at least one high
shear mixer, in a manner such that the rubber-modified asphalt
cement composition has an integration factor of at least 90.
[0011] Several embodiments of the invention, including the above
aspects of the invention, are described in further detail as
follows. Generally, each of these embodiments can be used in
various and specific combinations, and with other aspects and
embodiments unless otherwise stated herein.
BRIEF DESCRIPTION OF THE DRAWING
[0012] FIG. 1 illustrates an apparatus useful for preparing
rubber-modified asphalt cement.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The following detailed description, and the accompanying
drawings to which it refers, are provided describing and
illustrating certain examples or specific embodiments of the
invention only and not for the purpose of exhaustively describing
all possible embodiments and examples of the invention. Thus, this
detailed description does not in any way limit the scope of the
inventions claimed in this patent application or in any patent(s)
issuing form this or any related application.
[0014] To facilitate the understanding of the subject matter
disclosed herein, a number of terms, abbreviations or other
shorthand as used herein are defined below. Any term, abbreviation
or shorthand not defined is understood to have the ordinary meaning
used by a skilled artisan contemporaneous with the submission of
this application.
[0015] The term "asphalt" is used herein to mean any suitable
naturally-occurring asphalt or asphalt cement, synthetically
manufactured asphalt or asphalt cement, such as any asphalt that is
a by-product of a petroleum refining process, blown asphalt,
blended asphalt, residual asphalt, aged asphalt, petroleum asphalt,
straight-run asphalt, thermal asphalt, paving grade-asphalt,
performance graded asphalt cement, asphalt flux, bitumen, or the
like. Suitable performance graded asphalt cements include, for
example, any asphalt cements having the following characteristics
set forth in ASTM D6373-99, the contents of which are incorporated
herein by reference:
TABLE-US-00001 PG64-22 PG58-28 Asphalt Cement Asphalt Cement
Average 7-day max <58 <64 Pavement Design Temp, .degree. C.
Min. Pavement Design Temp, .degree. C. >-28 >-22 Original
Binder Flash Point Temp., D 92; min .degree. C. 230 230 Viscosity,
D4402: 135 135 max. 3 Pa s Test Temp., .degree. C. Dynamic Shear, P
246: 58 64 G.degree./sin.delta., min. 1.00 kPa 25 mm Plate, 1 mm
Gap Test Temp. at 10 rad/s, .degree. C. Rolling Thin Film Over
(Test Method D 2872) Mass Loss, max. percent 1.00 1.00 Dynamic
Shear, P 246: 58 64 G.degree./sin.delta., min. 2.20 kPa 25 mm
Plate, 1 mm Gap Test Temp. at 10 rad/s, .degree. C. Pressure Aging
Vessel Residue (AASHTO PP1) PAV Aging Temperature, .degree. C. 100
100 Dynamic Shear, P 246: 19 25 G.degree./sin.delta., min. 5000 kPa
8 mm Plate, 2 mm Gap Test Temp. at 10 rad/s, .degree. C. Creep
Stiffness, P 245: -18 -12 S, max 300 MPa, m-value; min. 0.300 Test
Temp at 60 s, .degree. C. Direct Tension, P 252: -18 -12 Failure
Strain, min. 1.0% Test Temp. at 1.0 mm/min, .degree. C.
[0016] Suitable asphalts also include, for example, any asphalt
cements having the following characteristics:
TABLE-US-00002 Asphalt AC-20 AC-5 cement flux ASTM # Orig. visc. at
140.degree. F. 1725 568 40 ASTM D2171 in poise Penetration at
77.degree. F. 57 153 300+ ASTM D5 100 g. 5 sec. dmm Softening point
.degree. F. 118 104 65 ASTM D36 Flash point .degree. F. (COC) 585
588 565 ASTM D92 Ductility at 39.2.degree. F. 0 5.5 15 ASTM D113 5
cm/min. cm
[0017] The term "rubber," as used herein, refers to any material
made substantially of rubber, such as, for example, virgin rubber,
recycled rubber (such as from tires, inner-tubes, gaskets, rubber
scrap, or the like), peel rubber, cured rubber, and/or processed
rubber of any polymer type(s), such as, for example, tire rubber
(e.g., scrap tire rubber, whole tire solid rubber, and/or scrap
whole tire rubber), non-solvent-treated rubber, non-pre-swelled
rubber, and/or any rubber that comprises less than about 5% (such
as less than about 3% or even 1%) of talc powder, such as wherein
the rubber has no insoluble materials such as metals, fibers,
cords, wood, rocks, dirt, and/or the like.
[0018] The term "granules," as used herein, refers to any suitable
form of rubber for use in preparing a rubber-modified asphalt
cement, such as particles, crumbs, and/or other particulate forms
(e.g., shavings, fines, beads, or the like), which can be produced
and/or processed in any manner (such as via vulcanization, ambient
grinding and/or cryogenic grinding). Moreover, granules can exist
in suitable size prior to formation of the rubber-modified asphalt
cement, such that, for example, greater than about 90 wt. % (such
as greater than about 95 wt. %, or even greater than about 99%) of
the rubber granules, relative to the total weight of the rubber
granules, have a size of less than about 20 mesh (such as less than
about 25 mesh, less than about 30 mesh, less than about 35 mesh,
less than about 40 mesh, less than about 45 mesh, less than about
50 mesh, less than about 60 mesh, less than about 70 mesh, or even
less than about 80 mesh) in accordance with U.S. Sieve series.
[0019] The term "integration" or "integration value" as used
herein, refers to the weight percent solubility of rubber-modified
asphalt cement in trichloroethylene, as determined via Standard
Test Method for Solubility of Asphalt Materials in TCE-ASTM D2042.
If, for example, a rubber-modified asphalt cement has a solubility
in trichloroethylene of 98 wt. %, then about 2 wt. % of the total
rubber introduced into the aphalt cement for integration has not
successfully integrated into the rubber modified asphalt cement.
The terms "fully integrated" and "fully incorporated," as used
herein, refer to a rubber-modified asphalt cement composition
having an integration value of at least 90 (such as at least 93, at
least 95, at least 96, at least about 97, at least about 98, at
least about 98.2, at least about 98.4, at least about 98.6, at
least about 98.8, at least about 99, at least about 99.2, at least
about 99.4, at least about 99.6, or even at least 99.8).
Preparation of Rubber-Modified Asphalt Cement
[0020] A rubber-modified asphalt cement (RMAC) having superior
properties can be prepared in any suitable manner by mixing,
blending, combining, and/or contacting asphalt and rubber granules
using a system or method that comprises at least one high shear
mixer or mill, under suitable conditions (e.g., a mixture
temperature maintained at greater than about 500.degree. F.) and
for a suitable duration to cause at least some (e.g., a substantial
amount or even all) of the rubber granules to be liquefied or
otherwise subsumed, incorporated, and/or integrated into the
asphalt base or medium without any significant and/or substantial
degradation and/or destruction of the base asphalt occurring. In
another embodiment, for example, the rubber granules and asphalt
are mixed without air blowing, jet spray agitation, oxidation,
and/or substantial distillation of the asphalt component. In some
embodiments, a high throughput system and method are provided for
fast, efficient, reduced cost production of fully integrated
rubber-modified asphalt cement.
[0021] In some embodiments, as illustrated in FIG. 1, asphalt is
charged into process vessel 102 having mixer 104 and is circulated
through heat exchanger 112 through line 108 via operation of
process feed pump 110. The process vessel 102 preferably has a top
exit 106 for removal of excess gaseous hydrocarbons and other
gaseous vapors, such as 112S, which are disposed of, for example,
by incineration at a temperature of about 1350.degree. F. A portion
or all of the asphalt can be recirculated through process feed pump
110 via line 114 having valve 116, such as to control, adjust,
and/or regulate the flow pressure of the asphalt at downstream
components of the system or apparatus (e.g., heat exchanger 112 and
pre-wet vessel 126).
[0022] Following passage through heat exchanger 112, some or all of
the asphalt can be routed back to process vessel 102 through line
118 having valve 120, such as, to maintain the temperature of, or
further heat, the asphalt (or asphalt/rubber mixture during later
production stages). The asphalt, in this manner, can be heated and
maintained at any suitable temperature (such as about
450-550.degree. F., about 460-540.degree. F., about 480-520.degree.
F., about 490-510.degree. F., e.g., at least about 460.degree. F.,
at least about 480.degree. F., at least about 490.degree. F., at
least about 500.degree. F., or at least about 510.degree. F.) via
circulation through heat exchanger 112, prior to being passed
through the remainder of the system.
[0023] All or some of the heated asphalt is then passed through
line 122 (having valve 124) to pre-wet vessel 126 for mixing with
rubber granules. Rubber granules, in turn, are charged into the
pre-wet vessel 126 via auger 128. The asphalt and rubber granules
come into contact in pre-wet vessel 126, to form a wetted
asphalt/rubber mixture. Such wetting of the rubber granules within
pre-wet vessel 126 can occur in any manner. In one embodiment, the
rubber granules are top loaded into pre-wet vessel 126, and a top
mounted mixer within pre-wet vessel 126 causes the asphalt base and
rubber granules to intermix. The pre-wet vessel, in this regard,
can be of any suitable size (e.g., a 1500+ gallon capacity, or even
a 2500+ gallon capacity), and the rubber granules can be charged
into the pre-wet vessel at any desired rate (e.g., at least 1500
pounds/hour, at least 2000 pounds/hour, at least 2500 pounds/hour,
or even at least 3000 pounds/hour).
[0024] The wetted asphalt/rubber mixture is pulled from pre-wet
vessel 126 by process return pump 132 through line 130 and towards
high shear mill 138. A portion or all of the asphalt/rubber mixture
can be recirculated through process return pump 132 via line 134
having valve 136, if desired, in order to control, adjust, and/or
regulate the flow pressure of the wetted asphalt/rubber mixture at
downstream components of the system or apparatus (e.g., high shear
mill 138).
[0025] In some embodiments, the operation of process return pump
132 and process feed pump 110 is synchronized in order to maintain
constant liquid levels within pre-wet vessel 126.
[0026] The wetted asphalt/rubber mixture then enters high shear
mixer 138, wherein the mixture is subjected to (or encounters) high
shear mixing that at least partially integrates and/or incorporates
the rubber granules into the asphalt base (thus forming a sheared,
heated mixture and/or an at least partially integrated
rubber-modified asphalt cement composition). The high shear mixer
used in the context of the present invention can be any suitable
mixer or mill (e.g., colloid mill) capable of high shear mixing
(and/or imparting mechanical shearing on) the asphalt and rubber
granules components. Suitable such high shear mixers include, for
example, any high shear mixers comprising paddles or fluid rotors,
such as any Siefer high shear mixer (e.g., a Seifer SMD3 300 HP
high shear mixer) or Silversen high shear mixer (e.g., Silversen
descending head shear mixer), or any other suitable high shear
mixer. The high shear mixer can comprise any suitable mill gap set,
such as, for example, a mill gap set of about 0.00001-1.0 inches
(such as about 0.00005-0.5 inches, about 0.0001-0.1 inches, about
0.0005-0.05 inches, about 0.0005-0.01 inches, or even about
0.001-0.0075 inches).
[0027] Following passage through high shear mill 138, the at least
partially integrated asphalt/rubber mixture circulates or passes
back to process vessel 102 through line 140, from where the mixture
can be circulate again through the system. In this manner,
circulation of the heated mixture through the system is continued,
with the temperature of the mixture being maintained at the desired
temperature (such as about 450-550.degree. F., about
460-540.degree. F., about 480-520.degree. F., about 490-510.degree.
F., e.g., at least about 460.degree. F., at least about 480.degree.
F. at least about 490.degree. F., at least about 500.degree. F., or
at least about 510.degree. F.), until the desired degree of
integration of the rubber granules into the asphalt medium is
achieved. Once a rubber-modified asphalt cement composition having
the desired integration factor is achieved, the composition is
pumped out of the system into a holding vessel before being
blended, oxidized, polymer modified, or shipped as is.
[0028] In operation, the asphalt component is charged to the
system, is heated, and is contacted with the rubber granules
component as the granules are charged to the system. The mixture of
asphalt and rubber granules can be passed (and concurrently heated
and/or maintained at a desired temperature) through all or some of
the system during the time required to charge all desired asphalt
and rubber components into the system. In some embodiments, some or
all of the asphalt component is heated (such as a temperature of at
least 500.degree. F.) prior to being contacted with the rubber
granules component. Following charging of all asphalt and rubber
granules into the system, the heated mixture of asphalt and rubber
granules components can be passed (or continued to be passed)
through the high shear mixer(s) for at least 30 minutes, as
measured from the time point at which all asphalt and rubber
granules components have been charged to the system and/or heated
to the desired temperature. In this regard, the asphalt and rubber
granules are continued to be mixed through the system or method
until the desired integration factor is achieved.
[0029] Any suitable duration of high shear mixing can be utilized
in the present invention, depending on the desired finished
properties of the rubber-modified asphalt cement. In some
embodiments, once the asphalt and rubber components are contacted
within the system, the mixture of asphalt and rubber is heated
(such as to a temperature of at least about 500.degree. F.), and
the heated mixture is passed and/or circulated through at least one
high shear mixer for greater than 30 minutes, greater than 45
minutes, greater than 60 minutes, greater than 75 minutes, greater
than 90 minutes, greater than 115 minutes, or even greater than 130
minutes, as measured from the time point at which all asphalt and
rubber granules components have been charged to the system and/or
heated to the desired temperature. In some embodiments, a fully
integrated rubber-modified asphalt cement composition is prepared
by passing and/or circulating a heated mixture of rubber and
asphalt through at least one high shear mill for less than 240
minutes, such as less than 200 minutes, less than 180 minutes, less
than 160 minutes, less than 140 minutes, less than 120 minutes, or
even less than 90 minutes, as measured from the time point at which
all asphalt and rubber granules components have been charged to the
system and/or heated to the desired temperature. In some
embodiments, a fully integrated rubber-modified asphalt cement
composition is prepared by passing and/or circulating a heated
mixture of rubber and asphalt through at least one high shear mill
for 30-240 minutes (such as greater than 30 minutes and less than
240 minutes), 30-200 minutes, 30-180 minutes, 30-150 minutes,
30-120 minutes, 35-240 minutes, 35-210 minutes, 35-180 minutes,
35-120 minutes, 40-240 minutes, 40-210 minutes, 40-180 minutes,
40-120 minutes, about 45-180 minutes, about 45-120 minutes, about
50-180 minutes about 50-120 minutes, about 60-180 minutes, about
60-150 minutes about 60-120 minutes, as measured from the time
point at which all asphalt and rubber granules components have been
charged to the system and/or heated to the desired temperature.
[0030] In some embodiments, a system and method are provided for
high throughput preparation of a fully integrated rubber-modified
asphalt cement composition comprising at least 40,000 pounds (such
as at least 45,000 pounds, at least 50,000 pounds, at least 52,000
pounds, at least 54,000 pounds, at least 56,000 pounds, at least
58,000 pounds, at least 60,000 pounds, at least 62,000 pounds, at
least 64,000 pounds, at least 66,000 pounds, at least 68,000
pounds, at least 70,000 pounds, at least 75,000, at least 80,000
pounds, at least 85,000 pounds, or at least 90,000 pounds) in a
period of less than 35 hours (such as less than 30 hours, less than
28 hours, less than 26 hours, less than 24 hours, less than 22
hours, less than 20 hours, less than 18 hours, less than 16 hours,
less than 14 hours, or even less than 12 hours), as measured from
the time point at which initial charging of the asphalt component
begins to the time point at which a fully integrated
rubber-modified asphalt cement product comprising all charged
asphalt and rubber granule components is produced. In some
embodiments, the high throughput system and method comprises
contacting asphalt with at least 40,000 pounds of rubber granules,
heating the mixture; and passing the heated mixture through at
least one high shear mixer. Alternatively, or in addition, the high
throughput system or method comprises contacting asphalt with at
least 40,000 pounds of rubber granules to form a mixture; heating
the mixture to a temperature of at least about 500.degree. F.; and
passing the heated mixture through at least one high shear mixer
for greater than 30 minutes. Alternatively, or in addition, the
high throughput system and method is performed using less than 1.2
million pounds (such as less than 1.0 million pounds; less than
800,000 pounds; less than 600,000 pounds; less than 400,000 pounds;
less than 300,000 pounds; less than 200,000 pounds; less than
150,000 pounds; less than 125,000 pounds; or even less than 100,000
pounds) of asphalt.
[0031] In one example embodiment, 156,000 pounds of asphalt and 26
super sacks (each containing 2000 pounds) were charged into a
system comprising a single high shear mixer, the tire rubber being
charged at a rate of 45 minutes/super sack. During the time
required to charge all of the asphalt and tire rubber components,
the already-charged portions of these asphalt and tire rubber
components were mixed, heated to 500.degree. F., and circulated
through the system. Once charging of the asphalt and tire rubber
components into the system was complete, and the complete mixture
was heated to the desired temperature, the heated mixture of
asphalt and tire rubber was passed (or continued to be passed)
through the high shear mixer and the remainder of the system for
two hours. From this process, a rubber-modified asphalt cement
composition comprising an integration value of at least 98 was
produced.
[0032] The rubber-modified asphalt cement composition can comprise
any desired amount of rubber. For example, the RMAC can comprise
greater than about 5 wt. %, such as greater than about 8 wt. %,
about 10 wt. %, about 12 wt. %, or even greater than about 14 wt. %
of rubber, relative to the total weight of the RMAC, and/or have a
rubber content in the range of about 5-15 wt. %, such as about 6-14
wt. %, about 7-13 wt. %, about 7.5-12.5 wt. %, about 8-12 wt. %,
about 8.5-12.5 wt. %, or even about 9-11 wt. %, relative to the
total weight of the RMAC, as well comprise one or more (including
all) of the properties described in this section of the application
(for example, rubber content, flash point, softening point,
penetration, and/or solubility). In another embodiment, the RMAC
can be more concentrated, i.e., having one or more properties (for
example, rubber content, flash point, softening point, penetration,
and/or solubility) different and/or higher than those desired for
the subsequent pre-treatment and/or emulsification steps. For
example, the RMAC can comprise greater than about 16 wt. %, about
18 wt. %, about 20 wt. %, about 25 wt. % about 30 wt. %, or even
greater than about 35 wt. % of rubber (relative to the total weight
of the RMAC), and/or have a rubber content in the range of about
16-35 wt. %, about 18-30 wt. %, about 20-35 wt. %, or about 20-30
wt. %, relative to the total weight of the RMAC. In this regard, in
the event that the RMAC has one or more properties (for example,
rubber content, flash point, softening point, penetration, and/or
solubility) that are higher than the desired properties for the
subsequent pre-treatment and/or emulsification steps, the RMAC can
be modified prior to these subsequent steps, such as by blending
the RMAC with asphalt. In one embodiment, for example, a RMAC
concentrate having greater than about 30 wt. % of rubber, relative
to the total weight of the RMAC, is blended (prior to the
pre-treatment and emulsification steps) with additional asphalt in
a manner such that the RMAC comprises about 5-15 wt. % of rubber,
relative to the total weight of the RMAC, as well as one or more
(including all) of the properties described in this section of the
application (for example, rubber content, flash point, softening
point, penetration, and/or solubility).
[0033] In one embodiment, the rubber within the RMAC has an average
size of less than about 20 microns, such as less than about 18
microns, about 16 microns, about 14 microns, about 12 microns,
about 11 microns, about 10 microns, about 9 microns, about 8
microns, about 7 microns, about 6 microns, about 5 microns, about 4
microns, about 3 microns, about 2 microns, about 1 micron, about
0.75 micron, about 0.5 micron, or even less than about 0.1 micron.
In another embodiment, greater than about 1% (such as greater than
about 3%, about 5%, about 10%, about 15%, or even greater than
about 10% by weight) of the rubber in the RMAC has an average size
of about 0.1-20 (such as about 1-15, about 5-15, about 5-20, about
10-20, or even about 10-15) microns, with the remainder of the
rubber having an average particle size of less than about 10 (such
as less than about 8, about 6, or even less than about 4) microns.
In another embodiment, the RMAC comprises less than about 8 wt. %
(such as less than about 6 wt. %, less than about 5 wt. %, less
than about 4 wt. %, less than about 3 wt. %, less than about 2 wt.
%, less than about 1 wt. %, less than about 0.5 wt. %, less than
about 0.25 wt. %, substantially no, or even no) rubber that is in a
solid state.
[0034] In one embodiment, the RMAC exhibits a solubility in
trichloroethylene (as determined via ASTM D2042) of at least about
90% (such as at least about 92%, at least about 94%, at least about
95%, at least about 96%, at least about 97%, at least about 98%, at
least about 98.2%, at least about 98.4%, at least about 98.6%, at
least about 98.8%, at least about 99%, at least about 99.2%, at
least about 99.4%, at least about 99.6%, or even at least 99.8%).
For example, it is preferred, in one embodiment, that when about 3
grams of the RMAC is dissolved in about 100 mL of trichloroethylene
and filtered through a 150 mm No. 52 filter paper, less than about
10 wt. % (such as less than about 8 wt. %, about 6 wt. %, about 5
wt. %, about 4 wt. %, about 3 wt. %, about 2 wt. %, about 1.8 wt.
%, about 1.6 wt. %, about 1.4 wt. %, about 1.2 wt. %, about 1 wt.
%, about 0.8 wt. %, about 0.6 wt. %, about 0.4 wt. %, or even less
than about 0.2 wt. %) of the RMAC remains on the filter paper
following such filtering.
[0035] Alternatively, or in addition, the RMAC exhibits a softening
point (as determined via ASTM D36) greater than about 90.degree.
F., such as greater than about 100.degree. F., or even greater than
about 110.degree. F.--a point at which, for example, a weight (such
as a steel ball having a diameter of about 9.5 mm and a mass of
about 3.50.+-.0.05 g) penetrates or settles at least about 1 inch
into a sample of the RMAC, using a ring and ball softening point
apparatus. In one preferred embodiment, the RMAC has a softening
point of about 115-125.degree. F.
[0036] Alternatively, or in addition, the RMAC comprises a
penetration at 77.degree. F. (as determined via ASTM D5) of less
than about 60 dmm, such as less than about 50 dmm, about 40 dmm,
about 30 dmm, about 20 dmm, or even less than about 10 dmm (such as
about 5-50 dmm, about 10-40 dmm, about 15-35 dmm, or even about
15-30 dmm), at which, for example, a 1 mm-diameter needle
penetrates into the RMAC at a needle load of about 100 grams for a
duration of about 5 seconds.
[0037] Alternatively, or in addition, the RMAC comprises a flash
point (as determined via ASTM D93) of at least about 460.degree.
F., such as at least about 480.degree. F., at least about
500.degree. F., at least about 510.degree. F., at least about
520.degree. F., at least about 530.degree. F., at least about
540.degree. F., or even at least about 550.degree. F.
[0038] In one embodiment, the RMAC is an asphalt cement concentrate
having the following properties:
[0039] In one embodiment, the RMAC comprises about 9-13 wt. % of
rubber (relative to the total weight of the RMAC), a penetration at
77.degree. F. (as determined via American Society for Testing and
Materials (ASTM) D5) of about 18-22 dmm, a softening point (as
determined via ASTM D36) greater than about 112.degree. F., and a
solubility in trichloroethylene (as determined via ASTM D2042) of
at least about 98%.
[0040] In some embodiments, in addition to the rubber and asphalt
components, other additives that enhance, cause, and/or assist in
devulcanization, liquefaction, and/or break-down of the rubber are
combined, mixed, contacted, and/or blended with the rubber and/or
asphalt components prior to and/or during contact of the rubber
granules and asphalt in preparing the RMAC. For example, such other
additives can aid in incorporation and/or combination of the rubber
into the asphalt component, and/or to adjust or alter the physical
properties (e.g., softening point, hardness, stability) of the
RMAC. For example, any anti-foam agents, polymer latex, and/or
sulfonic acids (e.g., DBSA and/or p-TSA) can be used in preparing
the RMAC, such as described in U.S. Pat. No. 5,496,400 (Doyle),
U.S. Pat. No. 7,087,665 (Sylvester), U.S. Pat. App. No.
2005/0131113, filed Feb. 7, 2005 (Sylvester), and/or U.S. Pat. App.
No. 2007/2049762, filed Jul. 10, 2006 (Sylvester). In some
preferred embodiments, however, no such other additives are used in
preparing the RMAC.
[0041] In another embodiment, a system is provided for preparing
the RMAC that comprises an asphalt charging device for charging
asphalt into the system; a rubber charging device for charging
rubber granules into the system; at least one heater for heating
the charged asphalt, the charged rubber granules, or a mixture
thereof; at least one high shear mixer for mixing the charged
asphalt and charged rubber granules into a rubber-modified asphalt
cement composition (i.e., for preparing the RMAC from the heated
mixture of charged asphalt and charged rubber granules components);
and a controller for controlling the asphalt charging device, the
rubber charging device, and/or the at least one high shear mixer,
in a manner such that the rubber-modified asphalt cement
composition has any desired integration factor. Additionally, as is
discussed herein, as is illustrated in FIG. 1, and as would be
appreciated by those of skill in the art, the system may further
comprise any additional components (such as lines, valves, input
conduits, output conduit, recycle loops, etc.) needed and/or
desired to optimize production of the RMAC and/or to enhance the
effectiveness, efficiency, speed, and/or other desirable properties
achievable through use of the system. In those embodiments in which
the system comprises two or more (e.g., three or more, four or
more, or even five or more) high shear mixers, such mixers can be
arranged in any desired manner, such as in series, in parallel, or
both. It should be noted that the system depicted in FIG. 1 is
provided for illustration purposes only, and is in no way intended
to be limiting.
[0042] The controller used in the present invention can be any
controller that is suitable for controlling, coordinating,
manipulating, and/or optimizing the operation of one or more
components of the system (such as, for example, the asphalt
charging device, the rubber charging device, and/or the at least
one high shear mixer of the present invention) in a manner such
that a rubber-modified asphalt composition having any desired
integration factor is produced. In some embodiments, the controller
is a semi-automatic controller that allows that any desired degree
of user input and/or control during the operation of the system. In
some embodiments, the controller is an automatic controller.
[0043] The systems and methods described herein are low energy,
energy efficient, and low cost systems and methods for the
production of rubber-modified asphalt cement compositions, as
compared to conventional systems and methods not comprising one or
more high shear mixers in combination with the other discussed
factors. In particular, for example, use of the present low energy
system and/or method to produce a rubber modified asphalt cement
composition from 52,000 pounds of rubber granules and having an
integration factor of 98, would require at least 5% (such as at
least 10%, at least 15%, at least 20%, at least 25%, or even at
least 40%) less energy, as compared to the energy required by a
conventional system to produce a rubber-modified asphalt cement
composition from 52,000 pounds of rubber granules and having an
integration factor of 95.
Other End Products
[0044] The RMAC can be used alone, or in combination with any other
components, to form any desired emulsions, slurry seals, surface
sealers, binder compositions, and/or other desired end products for
use in any desired application. In one embodiment, for example, a
composition comprising the RMAC can be applied to any paved
surface, such as any roadway, driving surface, and/or paved surface
(such as to form a seal-coat and/or surface sealer) in any suitable
manner (such as by computer rate control asphalt spreader truckers,
hand spray wands, and/or by squeegees) to form a cured coating.
Additionally, a composition comprised the RMAC can be applied to
any industrial surface (such as to enhance corrosion resistance of
steel, concrete, or the like, and/or to improve fire resistance of
such surfaces), any building surface such as any roof surface (such
as to form a seal-coat and/or surface sealer for the surface, such
as proximate to any asphalt roof surface such as asphalt roof
shingles), and/or the like, in any suitable manner. In other
embodiments, the composition comprising the RMAC can be form any
suitable industrial coating composition, surface sealer
composition, roof sealer composition, and/or roofing asphalt
cement, or the like. In all of these embodiments, the composition
comprising the RMAC can form a cured coating when applied to the
target surface.
[0045] Such end products comprising the RMAC can be prepared in any
suitable manner by combining, mixing, contacting, and/or blending
any desired amount of the RMAC with any corresponding amount of
other component(s) (e.g., emulsification solution) to produce a
composition having any desired properties (such as high and/or
enhanced resistance to water, fuel, and/or UV and/or no tackiness,
low tackiness, and/or substantially no tackiness properties), as
taught, for example, in U.S. Provisional Pat. App. 61/071,473,
filed Apr. 30, 2008, the contents of which are incorporated in
their entirety herein.
[0046] All publications and patent applications mentioned in this
specification are herein incorporated by reference to the same
extent as if each individual publication or patent application was
specifically and individually indicated to be incorporated by
reference.
[0047] It will be apparent to one of ordinary skill in the art that
many changes and modification can be made to the disclosures
presented herein without departing from the spirit or scope of the
appended claims.
* * * * *