U.S. patent application number 10/972022 was filed with the patent office on 2006-04-27 for use of inorganic acids with crosslinking agents in polymer modified asphalts.
This patent application is currently assigned to Fina Technology, Inc.. Invention is credited to Paul J. Buras, WIlliam Lee.
Application Number | 20060089429 10/972022 |
Document ID | / |
Family ID | 36206960 |
Filed Date | 2006-04-27 |
United States Patent
Application |
20060089429 |
Kind Code |
A1 |
Buras; Paul J. ; et
al. |
April 27, 2006 |
Use of inorganic acids with crosslinking agents in polymer modified
asphalts
Abstract
Asphalt and polymer mixtures treated with an inorganic acid and
crosslinked with sulfur and/or other crosslinkers or accelerators
gives a polymer modified asphalt with improved high temperature
properties. The acid should be added to the asphalt before the
crosslinker.
Inventors: |
Buras; Paul J.; (West
University Place, TX) ; Lee; WIlliam; (Humble,
TX) |
Correspondence
Address: |
FINA TECHNOLOGY INC
PO BOX 674412
HOUSTON
TX
77267-4412
US
|
Assignee: |
Fina Technology, Inc.
|
Family ID: |
36206960 |
Appl. No.: |
10/972022 |
Filed: |
October 22, 2004 |
Current U.S.
Class: |
524/59 |
Current CPC
Class: |
C08L 9/06 20130101; C08K
3/32 20130101; C08L 95/00 20130101; C08L 95/00 20130101; C08K 3/06
20130101; C08L 95/00 20130101; C08K 5/0025 20130101; C08L 2666/24
20130101; C08L 2666/04 20130101; C08K 3/24 20130101; C08L 2666/08
20130101; C08L 95/00 20130101; C08K 5/42 20130101 |
Class at
Publication: |
524/059 |
International
Class: |
C08L 95/00 20060101
C08L095/00 |
Claims
1. A method for preparing asphalt and polymer compositions
comprising: heating an asphalt; adding an elastomeric polymer and
an inorganic acid to the asphalt in any order to form a mixture,
where the proportion of inorganic acid ranges from about 0.05 to
about 2 wt % based on the total mixture; adding a crosslinker to
the mixture after the addition of the acid; and curing the mixture
to give a polymer modified asphalt (PMA).
2. The method of claim 1 where the elastomeric polymer is a vinyl
aromatic/conjugated diene elastomer.
3. The method of claim 2 where the elastomeric polymer is a
styrene-butadiene copolymer.
4. The method of claim 1 where the inorganic acid is selected from
the group consisting of phosphoric acid, polyphosphoric acid,
sulfuric acid, hydrochloric acid, nitric acid, and mixtures
thereof.
5. The method of claim 1 where the proportion of inorganic acid
ranges from about 0.05 to about 1 wt % based on the total
mixture.
6. The method of claim 1 where the crosslinker is selected from the
group consisting of sulfur, mercaptobenzothiazole and metal salts
thereof, thiurams, dithiocarbamates, sulfur-containing oxazoles,
thiazole derivatives, and mixtures thereof.
7. The method of claim 1 where the PMA has an improved high
temperature property as compared with an identical PMA absent the
inorganic acid, where the property is selected from the group
consisting of ODSR and RTFO fail temperatures and combinations
thereof.
8. The method of claim 1 where the elastomeric polymer comprises
from about 1 to about 20 wt % of the asphalt/polymer mixture.
9. The method of claim 1 where the crosslinker is present in an
amount ranging from about 0.01 to about 0.75 wt %, based on the
weight of the asphalt/polymer mixture.
10. The method of claim 1 further comprising adding a metal oxide
activator to the asphalt.
11. The method of claim 10 where the metal oxide activator is zinc
oxide.
12. A method for preparing asphalt and polymer compositions
comprising: heating an asphalt; adding an elastomeric
styrene-butadiene copolymer and an inorganic acid to the asphalt in
any order to form a mixture, where the proportion of inorganic acid
ranges from about 0.05 to about 1 wt % based on the total mixture;
adding a crosslinker to the mixture after the addition of the acid;
and curing the mixture to give a polymer modified asphalt
(PMA).
13. The method of claim 12 where the inorganic acid is selected
from the group consisting of phosphoric acid, polyphosphoric acid,
sulfuric acid, hydrochloric acid, nitric acid, and mixtures
thereof.
14. The method of claim 12 where the crosslinker is selected from
the group consisting of sulfur, mercaptobenzothiazoles and metal
salts thereof, thiurams, dithiocarbamates, sulfur-containing
oxazoles, thiazole derivatives, and mixtures thereof.
15. The method of claim 12 where the PMA has an improved high
temperature property as compared with an identical PMA absent the
inorganic acid, where the property is selected from the group
consisting of ODSR and RTFO fail temperatures and combinations
thereof.
16. The method of claim 12 where the elastomeric polymer comprises
from about 1 to about 20 wt % of the asphalt/polymer mixture.
17. The method of claim 12 where the crosslinker is present in an
amount ranging from about 0.01 to about 0.75 wt %, based on the
weight of the asphalt/polymer mixture.
18. The method of claim 12 where the PMA is produced in commercial
scale quantities.
19. The method of claim 12 further comprising adding a metal oxide
activator to the asphalt.
20. The method of claim 19 where the metal oxide activator is zinc
oxide.
21. A polymer modified asphalt (PMA) composition prepared by the
method comprising: heating an asphalt; adding an elastomeric
polymer and an inorganic acid to the asphalt in any order to form a
mixture, where the proportion of inorganic acid ranges from about
0.05 to about 2 wt % based on the total mixture; adding a
crosslinker to the mixture after the addition of the acid; and
curing the mixture to give a polymer modified asphalt (PMA).
22. The PMA of claim 21 where the elastomeric polymer is a vinyl
aromatic/conjugated diene elastomer.
23. The PMA of claim 22 where the elastomeric polymer is a
styrene-butadiene copolymer.
24. The PMA of claim 21 where the inorganic acid is selected from
the group consisting of phosphoric acid, polyphosphoric acid,
sulfuric acid, hydrochloric acid, nitric acid, and mixtures
thereof.
25. The PMA of claim 21 where the proportion of inorganic acid
ranges from about 0.05 to about 1 wt % based on the total
mixture.
26. The PMA of claim 21 where the crosslinker is selected from the
group consisting of sulfur, mercaptobenzothiazoles and metal salts
thereof, thiurams, dithiocarbamates, sulfur-containing oxazoles,
thiazole derivatives, and mixtures thereof.
27. The PMA of claim 21 where the PMA has an improved high
temperature property as compared with an identical PMA absent the
inorganic acid, where the property is selected from the group
consisting of ODSR and RTFO fail temperatures and combinations
thereof.
28. The PMA of claim 21 where the elastomeric polymer comprises
from about 1 to about 20 wt % of the asphalt/polymer mixture.
29. The PMA of claim 21 where the crosslinker is present in an
amount ranging from about 0.01 to about 0.75 wt %, based on the
weight of the asphalt/polymer mixture.
30. The PMA of claim 21 where the method further comprises adding a
metal oxide activator to the asphalt.
31. The PMA of claim 30 where the metal oxide activator is zinc
oxide.
32. A road made from the PMA of claim 21 and aggregate.
33. A roof sealed with the PMA of claim 21.
34. A method of sealing a roof with PMA comprising heating the PMA
of claim 21 and distributing it over at least a portion of roof
surface.
35. A method of road building comprising combining the PMA of claim
21 with aggregate to form a road paving material, and using the
material to form road pavement.
36. A polymer modified asphalt (PMA) composition prepared by the
method comprising: heating an asphalt; adding an elastomeric
styrene-butadiene copolymer and an inorganic acid to the asphalt in
any order to form a mixture, where the proportion of inorganic acid
ranges from about 0.05 to about 1 wt % based on the total mixture;
adding a crosslinker to the mixture after the addition of the acid;
and curing the mixture to give a polymer modified asphalt
(PMA).
37. The PMA of claim 36 where the inorganic acid is selected from
the group consisting of phosphoric acid, polyphosphoric acid,
sulfuric acid, hydrochloric acid, nitric acid, and mixtures
thereof.
38. The PMA of claim 36 where the crosslinker is selected from the
group consisting of sulfur, mercaptobenzothiazoles and metal salts
thereof, thiurams, dithiocarbamates, sulfur-containing oxazoles,
thiazole derivatives, and mixtures thereof.
39. The PMA of claim 36 where the PMA has an improved high
temperature property as compared with an identical PMA absent the
inorganic acid, where the property is selected from the group
consisting of ODSR and RTFO fail temperatures and combinations
thereof.
40. The PMA of claim 36 where the elastomeric polymer comprises
from about 1 to about 20 wt % of the asphalt/polymer mixture.
41. The PMA of claim 36 where the crosslinker is present in an
amount ranging from about 0.01 to about 0.75 wt %, based on the
weight of the asphalt/polymer mixture.
42. The PMA of claim 36 where the method further comprises adding a
metal oxide activator to the asphalt.
43. The PMA of claim 42 where the metal oxide activator is zinc
oxide.
44. A method of recycling asphalt comprising physically removing
asphalt from a location and reducing the size of the removed
asphalt, heating the removed asphalt, adding an inorganic acid to
the asphalt to form a mixture, adding a crosslinker to the mixture
after the acid is added.
45. The method of claim 44 further comprising an elastomeric
polymer to the asphalt.
46. Recycled asphalt made by the process of claim 44.
47. Aggregate comprising a PMA at least partially coating the
aggregate, where the PMA comprises asphalt, an elastomeric polymer,
an inorganic acid, and a crosslinker, where the crosslinker was
added to the asphalt after the inorganic acid.
Description
FIELD OF THE INVENTION
[0001] The present invention is related in one non-limiting
embodiment to hydrocarbon-based binders, such as bitumens, asphalts
and tars, modified with elastomers, and including a vulcanized
stage, which are particularly useful as industrial coatings and
road bitumens, or the like. It relates more particularly in another
non-restrictive embodiment to processes for obtaining vulcanized
compositions based on bitumens and on styrene/butadiene copolymers
that have acid incorporated therein to improve the properties of
the resulting polymer modified asphalts.
BACKGROUND OF THE INVENTION
[0002] The use of bitumen (asphalt) compositions in preparing
aggregate compositions (including, but not just limited to, bitumen
and rock) useful as road paving material is complicated by at least
three factors, each of which imposes a serious challenge to
providing an acceptable product. First, the bitumen compositions
must meet certain performance criteria or specifications in order
to be considered useful for road paving. For example, to ensure
acceptable performance, state and federal agencies issue
specifications for various bitumen applications including
specifications for use as road pavement. Current Federal Highway
Administration specifications require a bitumen (asphalt) product
to meet defined parameters relating to properties such as
viscosity, stiffness, penetration, toughness, tenacity and
ductility. Each of these parameters define a critical feature of
the bitumen composition, and compositions failing to meet one or
more of these parameters will render that composition unacceptable
for use as road pavement material.
[0003] Conventional bitumen compositions frequently cannot meet all
of the requirements of a particular specification simultaneously
and, if these specifications are not met, damage to the resulting
road can occur, including, but not necessarily limited to,
permanent deformation, thermally induced cracking and flexural
fatigue. This damage greatly reduces the effective life of paved
roads.
[0004] In this regard, it has long been recognized that the
properties of conventional bitumen compositions can be modified by
the addition of other substances, such as polymers. A wide variety
of polymers have been used as additives in bitumen compositions.
For example, copolymers derived from styrene and conjugated dienes,
such as butadiene or isoprene, are particularly useful, since these
copolymers have good solubility in bitumen compositions and the
resulting modified-bitumen compositions have good rheological
properties.
[0005] It is also known that the stability of polymer-bitumen
compositions can be increased by the addition of crosslinking
agents (vulcanizing agents) such as sulfur, frequently in the form
of elemental sulfur. It is believed that the sulfur chemically
couples the polymer and the bitumen through sulfide and/or
polysulfide bonds. The addition of extraneous sulfur may be helpful
to produce improved stability, even though bitumens naturally
contain varying amounts of native sulfur.
[0006] Thus, there are known processes for preparing a
bitumen-polymer composition consisting of mixing a bitumen, at
temperatures of about 266-446.degree. F. (130-230.degree. C.), with
2 to 20% by weight of a block or random copolymer, having an
average molecular weight between 30,000 and 300,000. The resulting
mixture is stirred for at least two hours, and then 0.1 to 3% by
weight of sulfur relative to the bitumen is added and the mixture
agitated for at least 20 minutes. The quantity of added sulfur can
be from about 0.1 to 1.5% by weight with respect to the bitumen.
The resulting bitumen-polymer composition is used for road-coating,
industrial coating, or other industrial applications.
[0007] Similarly, there are also known asphalt (bitumen) polymer
compositions obtained by hot-blending asphalt with from about 0.1
to 1.5% by weight of elemental sulfur and 1 to 7% by weight of a
natural or synthetic rubber, which can be a linear
butadiene/styrene copolymer. A process is additionally known for
preparing a rubber-modified bitumen by blending rubber, either
natural or synthetic, such as styrene/butadiene rubber, with
bitumen at 280-400.degree. F. (138-204.degree. C.), in an amount up
to 10% by weight based on the bitumen, then adjusting the
temperature to 257-320.degree. F. (125-160.degree. C.), and
intimately blending into the mix an amount of sulfur such that the
weight ratio of sulfur to rubber is between 0.01 and 0.9. A
catalytic quantity of a vulcanization-accelerator is also added to
effect vulcanization. A critical nature of the sulfur to rubber
ratio is sometimes reported, for instance that weight ratios of
sulfur to rubber of less than 0.01 gives modified bitumen of
inferior quality.
[0008] A second factor complicating the use of bitumen compositions
concerns the viscosity stability of such compositions under storage
conditions. In this regard, bitumen compositions are frequently
stored for up to 7 days or more before being used and, in some
cases, the viscosity of the composition can increase so much that
the bitumen composition is unusable for its intended purpose. On
the other hand, a storage stable bitumen composition would provide
for only minimal viscosity increases and, accordingly, after
storage it can still be employed for its intended purpose.
[0009] Asphaltic concrete, typically including asphalt and
aggregate, asphalt compositions for resurfacing asphaltic concrete,
and similar asphalt compositions must exhibit a certain number of
specific mechanical properties to enable their use in various
fields of application, especially when the asphalts are used as
binders for superficial coats (road surfacing), as asphalt
emulsions, or in industrial applications. (The term "asphalt" is
used herein interchangeably with "bitumen." Asphaltic concrete is
asphalt used as a binder with appropriate aggregate added,
typically for use in roadways.) The use of asphalt or asphalt
emulsion binders either in maintenance facings as a surface coat or
as a very thin bituminous mix, or as a thicker structural layer of
bituminous mix in asphaltic concrete, is enhanced if these binders
possess the requisite properties such as desirable levels of
elasticity and plasticity.
[0010] As noted, various polymers have been added to asphalts to
improve physical and mechanical performance properties.
Polymer-modified asphalts (PMAs) are routinely used in the road
construction/maintenance and roofing industries. Conventional
asphalts often do not retain sufficient elasticity in use and,
also, exhibit a plasticity range that is too narrow for use in many
modern applications such as road construction. It is known that the
characteristics of road asphalts and the like can be greatly
improved by incorporating into them an elastomeric-type polymer
which may be one such as butyl, polybutadiene, polyisoprene or
polyisobutene rubber, ethylene/vinyl acetate copolymer,
polyacrylate, polymethacrylate, polychloroprene, polynorbornene,
ethylene/propylene/diene (EPDM) terpolymer and advantageously a
random or block copolymer of styrene and a conjugated diene. The
modified asphalts thus obtained commonly are referred to variously
as bitumen/polymer binders or asphalt/polymer mixes. Modified
asphalts and asphalt emulsions typically are produced utilizing
styrene/butadiene based polymers, and typically have raised
softening point, increased viscoelasticity, enhanced force under
strain, enhanced strain recovery, and improved low temperature
strain characteristics as compared with non-modified asphalts and
asphalt emulsions.
[0011] The bituminous binders, even of the bitumen/polymer type,
which are presently employed in road applications often do not have
the optimum characteristics at low enough polymer concentrations to
consistently meet the increasing structural and workability
requirements imposed on roadway structures and their construction.
In order to achieve a given level of modified asphalt performance,
various polymers are added at some prescribed concentration.
[0012] Current practice is to add the desired level of a single
polymer, sometimes along with a reactant that promotes
cross-linking of the polymer molecules until the desired asphalt
properties are met. This reactant typically is sulfur in a form
suitable for reacting.
[0013] However, the cost of the polymer adds significantly to the
overall cost of the resulting asphalt/polymer mix. Thus, cost
factors weigh in the ability to meet the above criteria for various
asphalt mixes. In addition, at increasing levels of polymer
concentration, the working viscosity of the asphalt mix becomes
excessively great and separation of the asphalt and polymer may
occur.
[0014] It is common in the preparation of polymer-modified asphalts
to include activators and accelerators to make the crosslinking
reaction proceed faster. Zinc oxide (ZnO) is a conventional
activator, and mercaptobenzothiazole (MBT) is a conventional
accelerator. ZnO is also sometimes used to control the tendency of
the polymer to gel. The zinc salt of mercaptobenzothiazole (ZMBT)
combines features of both of these conventional additives.
[0015] As can be seen from the above, methods are known to improve
the mixing of asphalt and polymer compositions. The needed elements
for the commercial success of any such process include keeping the
process as simple as possible, reducing the cost of the
ingredients, and utilizing available asphalt cuts from a refinery
without having to blend in more valuable fractions. In addition,
the resulting asphalt composition must meet the above-mentioned
governmental physical properties and environmental concerns. Thus,
it is a goal of the industry to maintain or reduce the cost of the
polymers and crosslinking agents added to the asphalt without
sacrificing any of the other elements and improving the properties
of the asphalt and polymer compositions as much as possible.
SUMMARY OF THE INVENTION
[0016] There is provided, in one non-restrictive form, a method for
preparing asphalt and polymer compositions that involves heating an
asphalt, adding an elastomeric polymer and an inorganic acid to the
asphalt in any order to form a mixture, where the proportion of
inorganic acid ranges from about 0.05 to about 2 wt % based on the
total mixture. A crosslinker is added to the mixture after the
addition of the acid. The crosslinker may be added before or after
the polymer. The mixture is then cured to give a polymer modified
asphalt (PMA). In one non-limiting embodiment, the PMA has an
improved high temperature property as compared with an identical
PMA absent the inorganic acid, where the property is ODSR and/or
RTFO fail temperatures. In one non-restrictive embodiment, the PMA
is produced in commercial scale quantities, which may include a
quantity sufficient to surface a roof or a quantity sufficient to
surface a road, and the like.
[0017] In another non-restrictive embodiment, there are provided
polymer modified asphalt (PMA) compositions prepared by heating an
asphalt and adding an elastomeric polymer and an inorganic acid to
the asphalt in any order to form a mixture. The proportion of
inorganic acid ranges from about 0.05 to about 2 wt % based on the
total mixture. A crosslinker is added to the mixture after the
addition of the acid. The mixture is cured to give a polymer
modified asphalt (PMA). The innovations herein include roads made
from these PMAs as well as methods of building such roads, and
roofs sealed with these PMAs along with methods for sealing roofs
with these PMAs. Recycled asphalts incorporating the PMAs herein
may be used, and aggregates coated with the PMAs herein are also
contemplated.
DETAILED DESCRIPTION OF THE INVENTION
[0018] It has been discovered that improvements in rubber/asphalt
compatibility may be obtained by treating an asphalt with acid
prior to the addition of a crosslinker, where the polymer may be
added at any time. While acid treatments of asphalts are known, it
is unknown that the sequence of addition makes a difference in the
properties or quality of the asphalt produced. Adding the acid to
the asphalt prior to the crosslinker, or a substantially effective
amount of crosslinker, gives a polymer modified asphalt with
improved high temperature properties. These improved properties
include, but are not necessarily limited to, ODSR fail temperature
(original DSR) and RTFO fail temperature. By a "substantially
effective amount of crosslinker" is meant enough to crosslink to a
measurable extent.
[0019] As used herein, the term "bitumen" (sometimes referred to as
"asphalt") refers to all types of bitumens, including those that
occur in nature and those obtained in petroleum processing. The
choice of bitumen will depend essentially on the particular
application intended for the resulting bitumen composition.
Bitumens that can be used can have an initial viscosity at
140.degree. F. (60.degree. C.) of 600 to 3000 poise (60 to 300
Pa-s) depending on the grade of asphalt desired. The initial
penetration range (ASTM D5) of the base bitumen at 77.degree. F.
(25.degree. C.) is 20 to 320 dmm, and can be 50 to 150 dmm, when
the intended use of the copolymer-bitumen composition is road
paving. Bitumens that do not contain any copolymer, sulfur, etc.,
are sometimes referred to herein as a "base bitumen."
[0020] "Elastomeric Polymers" are natural or synthetic rubbers and
include, but are not necessarily limited to, butyl, polybutadiene,
polyisoprene or polyisobutene rubber, ethylene/vinyl acetate
copolymer, polyacrylate, polymethacrylate, polychloroprene,
polynorbornene, ethylene/propylene/diene (EPDM) terpolymer and
advantageously a random or block copolymer of a vinyl aromatic
compound, e.g. styrene, and conjugated dienes. In one non-limiting
embodiment, styrene/conjugated diene block copolymers may be used
that are linear, radial, or multi-branched. Styrene/butadiene and
styrene/isoprene copolymers having an average molecular weight of
between 30,000 and 300,000 have been found to be particularly
useful.
[0021] "Conjugated dienes" refer to alkene compounds having 2 or
more sites of unsaturation wherein a second site of unsaturation is
conjugated to a first site of unsaturation, i.e., the first carbon
atom of the second site of unsaturation is gamma (at carbon atom 3)
relative to the first carbon atom of the first site of
unsaturation. Conjugated dienes include, by way of non-limiting
example, butadiene, isoprene, 1,3-pentadiene, and the like.
[0022] "Block copolymers of styrene and conjugated-dienes" refer to
copolymers of styrene and conjugated-dienes having a linear or
radial, tri-block structure consisting of styrene-conjugated
diene-styrene block units that are copolymers are represented by
the formula: S.sub.x-D.sub.y-S.sub.z where D is a conjugated-diene,
S is styrene, and x, y and z are integers such that the number
average molecular weight of the copolymer is from about 30,000 to
about 300,000. These copolymers are well known to those skilled in
the art and are either commercially available or can be prepared
from methods known in the art. Such tri-block copolymers may be
derived from styrene and a conjugated-diene, wherein the
conjugated-diene is butadiene or isoprene. Such copolymers may
contain 15 to 50 percent by weight copolymer units derived from
styrene, alternatively may contain 20 to 35 percent derived from
styrene, and then again may contain 28 to 31 percent derived from
styrene, the remainder being derived from the conjugated diene.
These copolymers may have a number average molecular weight range
between about 50,000 and about 200,000, and alternatively have a
number average molecular weight range between about 80,000 and
about 180,000. The copolymer can employ a minimal amount of
hydrocarbon oil in order to facilitate handling. Examples of
suitable solvents include plasticizer solvent that is a
non-volatile aromatic oil. However, when the hydrocarbon oil is a
volatile solvent (as defined above), care should be taken to ensure
that the amount of solvent contained in the final bitumen
composition is less than about 3.5 weight percent.
[0023] In one non-limiting embodiment, the elastomeric polymer is
present in a proportion of from about 1 to about 20 wt % of the
asphalt/polymer mixture. In another, non-restrictive form, the
polymer is present in an amount of from about 1 to about 6 wt % of
the mixture.
[0024] The term "sulfur is defined herein as elemental sulfur in
any of its physical forms, whereas the term sulfur-containing
derivative" includes any sulfur-donating compound, but not
elemental sulfur. Sulfur-donating compounds are well known in the
art and include various organic compositions or compounds that
generate sulfur under the mixing or preparation conditions. In one
non-limiting embodiment, the elemental sulfur is in powder form
known as flowers of sulfur. Other sulfur-containing derivatives or
species that can be used herein include, but are not necessarily
limited to mercaptobenzothiazole, thiurams, dithiocarbamates,
sulfur-containing oxazoles, thiazole derivatives, and the like, and
combinations thereof. "Thiazole derivatives" include, but are not
necessarily limited to, compounds having the necessary functional
group to serve as sulfur donors, such as --N.dbd.C(R)--S--,
including oxazoles. In another non-limiting embodiment, the sulfur
and/or other crosslinker is present in an amount ranging from about
0.01 to about 0.75 wt %, alternatively from about 0.06% to about
0.3 wt. % based on the asphalt, and in another non-limiting
embodiment is present in an amount from about 0.08 to about 0.2 wt.
%. As noted earlier, the zinc salt of mercaptobenzothiazole (ZMBT)
combines features of conventional additives. Other metal salts of
MBT may also be useful.
[0025] Acceptable crosslinkers, in one non-limiting embodiment, are
thiuram polysulfides. In another non-limiting embodiment, the
thiuram polysulfides have the formula: ##STR1## where R.sup.1 and
R.sup.2 are the same or different alkyl substituents having from 1
to 4 carbon atoms, and wherein M is a metal selected from zinc,
barium or copper, and n is 0 or 1. In another non-limiting
embodiment, a crosslinking temperature range for thiuram
polysulfides of formula (I) is above 180.degree. C. (356.degree.
F.), alternatively, the crosslinking temperature range may be
between about 130 and about 205.degree. C. (280-400.degree. F.).
Thiuram polysulfides herein include, but are not limited to, zinc
dialkyldithiocarbamates such as dimethyldithiocarbamate.
[0026] The term "desired Rheological Properties" refers primarily
to the SUPERPAVE asphalt binder specification designated by AASHTO
as MP1 as will be described below. Additional asphalt
specifications can include viscosity at 140.degree. F. (60.degree.
C.) of from 1600 to 4000 poise (160400 Pa-s) before aging; a
toughness of at least 110 inch-pound (127 cm-kilograms) before
aging; a tenacity of at least 75 inch-pound (86.6 cm-kilograms)
before aging; and a ductility of at least 25 cm at 39.2.degree. F.
(4.degree. C.) at 5 cm/min. pull rate after aging.
[0027] Viscosity measurements are made by using ASTM test method
D2171. Ductility measurements are made by using ASTM test method
D113. Toughness and tenacity measurements are made by a Benson
Method of Toughness and Tenacity, run at 20 inches/minute (50.8
cm/minute) pull rate with a 1/8 inch (2.22 cm) diameter ball.
[0028] By "storage stable viscosity" it is meant that the bitumen
composition shows no evidence of skinning, settlement, gelation, or
graininess and that the viscosity of the composition does not
increase by a factor of four or more during storage at
325.+-.0.5.degree. F. (163.+-.2.8.degree. C.) for seven days. In
one non-restrictive version, the viscosity does not increase by a
factor of two or more during storage at 325.degree. F. (163.degree.
C.) for seven days. In another non-limiting embodiment, the
viscosity increases less than 50% during seven days of storage at
325.degree. F. (163.degree. C.). A substantial increase in the
viscosity of the bitumen composition during storage is not
desirable due to the resulting difficulties in handling the
composition and in meeting product specifications at the time of
sale and use.
[0029] The term "aggregate" refers to rock and similar material
added to the bitumen composition to provide an aggregate
composition suitable for paving roads. Typically, the aggregate
employed is rock indigenous to the area where the bitumen
composition is produced. Suitable aggregate includes granite,
basalt, limestone, and the like.
[0030] As used herein, the term "asphalt cement" refers to any of a
variety of substantially solid or semi-solid materials at room
temperature that gradually liquify when heated. Its predominant
constituents are bitumens, which may be naturally occurring or
obtained as the residue of refining processing. As mentioned, the
asphalt cements are generally characterized by a penetration (PEN,
measured in tenths of a millimeter, dmm) of less than 400 at
25.degree. C., and a typical penetration range between 40 and 300
(ASTM Standard, Method D-5). The viscosity of asphalt cement at
60.degree. C. is more than about 65 poise. Asphalt cements are
alternately defined in terms specified by the American Association
of State Highway Transportation Officials (AASHTO) AR viscosity
system.
[0031] The asphalt terms used herein are well known to those
skilled in the art. For an explanation of these terms, reference is
made to the booklet SUPERPAVE Series No. 1 (SP-1), 1997 printing,
published by the Asphalt Institute (Research Park Drive, P.O. Box
14052, Lexington, Ky. 405124052), which is hereinafter referred to
as MP1 (Standard Specification for Performance Graded Asphalt
Binder). For example, Chapter 2 provides an explanation of the test
equipment, terms, and purposes. Rolling Thin Film Oven (RTFO) and
Pressure Aging Vessel (PAV) are used to simulate binder aging
(hardening) characteristics. Dynamic Shear Rheometers (DSR) are
used to measure binder properties at high and intermediate
temperatures. These are used to predict permanent deformation or
rutting and fatigue cracking. Bending Beam Rheometers (BBRs) are
used to measure binder properties at low temperatures. These values
predict thermal or low temperature cracking. The procedures for
these experiments are also described in the above-referenced
SUPERPAVE booklet.
[0032] Asphalt grading is given in accordance with accepted
standards in the industry as discussed in the above-referenced
Asphalt Institute booklet. For example, pages 62-65 of the booklet
include a table entitled Performance Graded Asphalt Binder
Specifications. The asphalt compositions are given performance
grades, for example, PG 64-22. The first number, 64, represents the
average 7-day maximum pavement design temperature in .degree. C.
The second number, -22, represents the minimum pavement design
temperature in .degree. C. Other requirements of each grade are
shown in the table. For example, the maximum value for the PAV-DSR
test (.degree. C.) for PG 64-22 is 25.degree. C.
[0033] One of the methods commonly utilized in the industry to
standardize the measure or degree of compatibility of the rubber
with the asphalt is referred to as the compatibility test.
Compatibility tests provide a measure of the degree of separability
of materials comprising the asphalt. The long-term compatibility
between rubber and the other components of PMA, for example, is an
important consideration when preparing road material. If rubber is
not compatible with the other components of PMA, then the
performance of road materials containing PMA is degraded.
Compatibility is assessed by measuring the softening point of
asphalt after a period of thermally-induced aging (for example
Louisiana DOTD Asphalt Separation of Polymer Test Method TR 326).
The test is performed on a polymer-modified asphalt mixture
comprised of rubber and asphalt with all the applicable additives,
such as the crosslinking agents. The mixture is placed in tubes,
usually made of aluminum or similar material, referred to as cigar
tubes or toothpaste tubes. These tubes are about one inch (2.54 cm)
in diameter and about fifteen centimeters deep. The mixture is
placed in an oven heated to a temperature of about 162.degree. C.
(320.degree. F.). This temperature is representative of the most
commonly used asphalt storage temperature. After the required
period of time, most commonly twenty-four (24) hours, the tubes are
transferred from the oven to a freezer and cooled down to solidify.
The tubes are kept in the vertical position. After cooling down,
the tubes are cut into thirds; three equal sections. The Ring and
Ball softening point of the top one third is compared to the
softening point of the bottom section. This test gives an
indication of the separation or compatibility of the rubber within
the asphalt. The rubber would have the tendency to separate to the
top. The lower the difference in softening point between the top
and bottom sections, the more compatible are the rubber and
asphalt. In today's environment, many states require a difference
of 4.degree. F. (2.degree. C.) or less to consider the
asphalt/rubber composition as compatible. Few standards allow a
higher difference. The twenty-four hour test is used as a common
comparison point. In one non-limiting embodiment, this
compatibility test value is 20.degree. C. or less.
[0034] In accordance with one non-restrictive embodiment, an
asphalt composition is prepared by adding the asphalt or bitumen to
a mixing tank that has stirring means. The asphalt is added and
stirred at elevated temperatures. Stirring temperatures depend on
the viscosity of the asphalt and can range up to 500.degree. F.
(260.degree. C.). Asphalt products from refinery operations are
well known in the art. For example, asphalts typically used for
this process are obtained from deep vacuum distillation of crude
oil to obtain a bottom product of the desired viscosity or from a
solvent deasphalting process that yields a demetallized oil, a
resin fraction and an asphaltene fraction. Some refinery units do
not have a resin fraction. These materials or other compatible oils
of greater than 450.degree. F. (232.degree. C.) flash point may be
blended to obtain the desired viscosity asphalt.
[0035] Rubbers, elastomeric polymers, or thermoplastic elastomers
suitable for this application are well known in the art as
described above. For example, FINAPRENE.RTM. SBS rubber products
available from Atofina Elastomers Inc. are suitable for the
applications herein. This example is not limiting for the inventive
technology that can be applied to any similar elastomeric product
particularly those produced from styrene and butadiene.
[0036] It has been found that the addition of inorganic acids to
the asphalts improves the properties thereof, and it has been
surprisingly discovered that the addition of the acid prior to the
crosslinker particularly gives better results. It is not known by
what mechanism this phenomenon occurs, such as whether by oxidizing
or crosslinking, and the invention is not limited to any particular
mechanism or explanation, although the asphalt seems to be hardened
by this method.
[0037] Suitable inorganic acids for use in the methods herein
include, but are not necessarily limited to, phosphoric acid,
polyphosphoric acid, sulfuric acid, hydrochloric acid, nitric acid,
and mixtures thereof. Herein, phosphoric acid includes
polyphosphoric acid. In one non-limiting embodiment, the proportion
of inorganic acid ranges from about 0.05 to about 2 wt % based on
the total mixture of asphalt, acid and polymer. In another
non-restrictive embodiment, the proportion of inorganic acid ranges
from about 0.05 to about 1 wt % based on the total mixture.
[0038] In another non-restrictive embodiment, a metal oxide
activator is also present in the asphalt/polymer mixture herein. As
mentioned, zinc oxide is a known, conventional activator, and can
also be used to suppress the evolution of hydrogen sulfide. Other
useful metal oxides include, but are not necessarily limited to,
CaO, MgO and CuO as discussed in U.S. Patent Application
2004/0030008 A1, incorporated by reference herein. In one
non-restrictive form, the acid is present in an equimolar amount of
the ZnO present.
[0039] Various other additives suitable for the purposes herein
include, but are not necessarily limited to, known and future
accelerators, activators, divalent metal oxides (e.g. zinc oxide)
and the like. A variety of accelerators may be used in conjunction
herein, including, but not limited to, dithiocarbamates and
benzothiazoles. Many crosslinking agents and other additives are
normally sold in powder or flake form.
[0040] The methods and compositions described will be further
illustrated with respect to particular Examples that are only
intended to more fully illuminate the compositions and methods and
not limit them.
EXAMPLES 1-6
[0041] Phosphoric acid in low concentrations improved the
high-temperature MP1 properties of neat and polymer modified
asphalt. Concentrations of acid from 0.1 to 0.3 wt % improved the
ODSR Fail Temperature of neat asphalt by 2 to 2.5.degree. C. The
RTFO DSR Fail Temperature of neat asphalt was improved by
approximately 4.degree. C. at 0.1 to 0.3 wt % acid. The limiting
RTFO DSR Fail Temperature of PMA with 0.1 to 0.3 wt % phosphoric
acid was raised 3 to 4.degree. C. Low temperature properties were
not significantly affected.
[0042] The materials used in Examples 1-6 included a base asphalt,
FINAPRENE 502 SBS polymer (FP502), ZnO, MBT, sulfur, and phosphoric
acid. The experimental formulation and initial procedures are given
in Table I. TABLE-US-00001 TABLE I Formulations of Examples 1-6
Example Formulation and Initial Procedure 1 Grade the base asphalt
according to MP1. 2 Formulate a blend composed of 99.9 wt % base
asphalt and 0.1 wt % phosphoric acid; MP1 grade. 3 Formulate a
blend composed of 99.7 wt % base asphalt and 0.3 wt % phosphoric
acid; MP1 grade. 4 Formulate a PMA (Control) blend composed of 96
wt % base asphalt and 4 wt % FP502; crosslink with 0.06 wt %
ZnO/0.06 wt % MBT/0.12 wt % S. Test for compatibility, MP1 grade,
and measure the 135.degree. C. Viscosity. 5 Formulate a PMA blend
composed of 96 wt % base asphalt, 4 wt % FP502, and 0.1 wt %
phosphoric acid; crosslink with 0.6 ZnO/0.06 MBT/0.12 S. Test for
Compatibility, MP1 Grade, and measure the 135.degree. C. Viscosity.
6 Formulate a PMA blend composed of 96 wt % base asphalt, 4 wt %
FP502, and 0.3 wt % phosphoric acid; crosslink with 0.6 ZnO/0.06
MBT/0.12 S. Test for Compatibility, MP1 Grade, and measure the
135.degree. C. Viscosity.
Procedure
[0043] The asphalt sample was heated to 350.degree. F. (177.degree.
C.) with low shear mixing. The designated acid was added and
stirring the sample continued for 10 minutes. PMA formulations were
mixed according to the following procedure, after acid addition
(where applicable):
[0044] The asphalt sample was heated to 350.degree. F. (177.degree.
C.) with low shear mixing. The mixing was changed to high shear and
the polymer added. Mixing continued on high shear for 1 hour at
350.degree. F. (177.degree. C.). The mixing was reduced to low
shear. The crosslinking agents were added and mixing continued on
low shear at 350.degree. F. (177.degree. C.) for 1 hour. The PMA
mixture was aged in the oven at 325.degree. F. (163.degree. C.) for
24 hours. The cured asphalt was tested for 24/48-hour
Compatibility, MP1 grade, and the 135.degree. C. Rotational
Viscosity measured. Observations were noted (e.g. gelling, film
formation, lumps, smoke, etc.).
[0045] Test results for the blends of neat asphalt modified with
phosphoric acid are presented in Table II. TABLE-US-00002 TABLE II
Base Asphalt Modified with Phosphoric Acid Examples Units 1
(Control) 2 (Inv.) 3 (Inv.) Base Asphalt Wt % 100 99.9 99.7
Phosphoric Acid Wt % 0.1 0.3 Binder DSR .degree. C. 66.3 68.2 68.8
RTFO DSR .degree. C. 67.8 71.7 72.3 PAV DSR .degree. C. 23.0 24.0
25.1 m-Value .degree. C. -14.8 -14.1 -14.0 S-Value .degree. C.
-15.8 -16.2 -16.4
[0046] As shown in Example 2, the addition of 0.1 wt % phosphoric
acid only raised the ODSR (original DSR or binder DSR) Fail
Temperature by 1.9.degree. C. However, the RTFO DSR Fail
Temperature was improved by 3.9.degree. C. An increase in the
phosphoric acid concentration to 0.3 wt % (Example 3) marginally
improved the high-temperature properties, compared to the blend
with 0.1 wt % additive phosphoric acid. There was no change in
low-temperature properties with phosphoric acid addition. There was
a slight increase in the PAV DSR Fail Temperature upon acid
addition. The increase in PAV DSR Fail Temperature could be a
concern in asphalts where PAV DSR Fail Temperature is at or near
the specification maximum of 25.degree. C.
[0047] PMA produced from the phosphoric acid-treated base stock
showed improvement in high-temperature properties. The test results
from the PMA blends are presented in Table III. TABLE-US-00003
TABLE III PMA formulated from Base Asphalt Treated with Phosphoric
Acid. Examples Units 1 (Cont.) 4 (Cont.) 5 (Inv.) 6 (Inv.) Base
Asphalt Wt % 100 96 96 96 FP502 Wt % 4 4 4 ZnO Wt % 0.06 0.06 0.06
MBT Wt % 0.06 0.06 0.06 Sulfur Wt % 0.12 0.12 0.12 Phosphoric Acid
0.1 0.3 Binder DSR .degree. C. 66.3 83.4 85.3 86.7 RTFO DSR
.degree. C. 67.8 81.2 84.6 85.0 PAV DSR .degree. C. 23.0 -18.8 21.1
20.7 m-Value .degree. C. -14.8 -17.5 -16.5 -16.4 S-Value .degree.
C. -15.8 -20.4 -20.7 -20.2 48 hr .degree. F. 4.7 1.4 6.6
Compatibility (.degree. C.) (2.6) (0.78) (3.7) 48 hr .degree. F.
N/A 0.7 18.3 Compatibility (.degree. C.) (0.39) (10.2) 135.degree.
C. Pa*s 1.92 2.35 2.85 Viscosity
[0048] Addition of 0.1 wt % phosphoric acid to the PMA raised the
ODSR Fail Temperature of the PMA by 1.9.degree. C. More
importantly, the MP-1-limiting RTFO DSR Fail Temperature was raised
by 3.4.degree. C., showing an improvement in the high-temperature
MP1 properties. There was a slight increase in the PAV DSR Fail
Temperature of the PMA, but the final PAV DSR Fail Temperature was
well below the specification maximum of 28.degree. C. The
low-temperature properties were effectively unchanged. The PMA
formulated from the base treated with 0.1 wt % phosphoric acid was
rubber compatible with a separation of 0.7.degree. F. (0.39.degree.
C.) after 48 hrs. The PMA formulated from the base treated with 0.3
wt % phosphoric acid was not compatible with a measured separation
of 18.3.degree. F. (10.2.degree. C.) after 48 hrs. The MP1
properties of the 0.3 wt % acid-treated PMA were not significantly
improved compared to the PMA from the 0.1 wt %-treated base.
EXAMPLES 7-14
[0049] In Examples 1-6, acid addition was shown to have beneficial
effects on the high-temperature properties of neat asphalt and PMA.
A second asphalt base stock, with poor high-temperature MP1
properties when modified with rubber, was treated with phosphoric
or sulfuric acid, and tested for MP1 properties in Examples 7-14.
The PMA was formulated from the acid-treated base stock, or the PMA
was treated with acid after crosslinking.
[0050] The materials used in Examples 7-14 included the second base
asphalt, FINAPRENE 502 SBS polymer (FP502), ZnO, MBT, sulfur,
phosphoric acid and sulfuric acid. The experimental formulation and
initial procedures are given in Table IV. Zinc oxide in the amount
of 0.2 wt % was added to the base stock before MP1 grading or PMA
formulation TABLE-US-00004 TABLE IV Formulations of Examples 7-14
Ex. Formulation and Initial Procedure 7 MP1 Grade second base
asphalt. 8 2.0% FP502 in 98% second base asphalt, crosslinked with
0.06 wt % MBT/12 wt % S. 9 Treatment of asphalt with 0.1 wt %
sulfuric acid. 10 Treatment with 0.1 wt % sulfuric acid followed by
polymer modification with 2.0 wt % FP502 in 98% second base
asphalt, crosslinked with 0.06 MBT/12S. 11 Polymer modification
with 2.0% FP502 in 98% second base asphalt, crosslinked with 0.06
MBT/12S; treated with 0.1 wt % sulfuric acid one hour after
crosslinker addition. 12 Treatment of asphalt with 0.1 wt %
phosphoric acid. 13 Treatment with 0.1 wt % phosphoric acid
followed by polymer modification with 2.0% FP502 in 98% second base
asphalt, crosslinked with 0.06 MBT/12S. 14 Polymer modification
with 2.0% FP502 in 98% second base asphalt, crosslinked with 0.06
MBT/12S; treat with 0.1 wt % phosphoric acid one hour after
crosslinker addition.
Procedure
[0051] The following mixing procedures were used for the
acid-modified asphalt and PMA blends:
[0052] The asphalt was heated to 350.degree. F. (177.degree. C.)
with low shear mixing. The specified acid was added and the mixture
stirred for 10 minutes. For blends with no additional polymer
modification, heating continued at 350.degree. F. (177.degree. C.)
for one 10 hour. The mixture was aged for 24 hrs at 325.degree. F.
(163.degree. C.).
[0053] For PMA blends, please note when the acid addition was made.
Mixing was set to high shear and the FP502 polymer added. Mixing
continued on high shear for 1 hour at 350.degree. F. (177.degree.
C.). Mixing was reduced to low shear. The crosslinking agents were
added and mixing continued on low shear at 350.degree. F.
(177.degree. C.) for 1 hour. The PMA mixture was aged in the oven
at 325.degree. F. (163.degree. C.) for 24 hours. The resulting
cured asphalts were tested for 48-hour compatibility and were MP1
graded. The 135.degree. C. Brookfield Viscosity values were
measured. Observations were noted (e.g. gelling, film formation,
lumps, smoke, etc.).
[0054] Treatment of the neat asphalt with 0.1 wt % sulfuric acid
(Comparative Example 9) resulted in only modest improvement in the
limiting RTFO DSR Fail Temperature and no improvement in the ODSR
Fail Temperature. The PAV DSR Fail Temperature was increased
outside of the specification maximum of 25.degree. C. There was no
change in the low-temperature properties. PMA produced from the
sulfuric acid-treated base (Inventive Example 10) showed no
effective change in the ODSR Fail Temperature, compared to the
Control Blend (Comparative Example 9), but did show a 3.degree. C.
improvement in the limiting RTFO DSR Fail Temperature. The results
were intermediate for the PMA in which the acid was added after
crosslinking (Comparative Example 11). Test results for the blends
treated with sulfuric acid are presented in Table V. TABLE-US-00005
TABLE V Properties of PAR asphalt and PMA treated with sulfuric
acid. 7 8 9 10 11 Units (Comp.) (Comp.) (Comp.) (Inv.) (Comp.)
Second base Wt % 100 99.9 98 98 98 asphalt Sulfuric Acid Wt % 0.1
0.1* 0.1** FP502 Wt % 2 2 2 MBT Wt % 0.06 0.06 0.06 Sulfur Wt %
0.12 0.12 0.12 Binder DSR .degree. C. 65.9 66.9 71.4 71.0 71.5 RTFO
DSR .degree. C. 64.9 67.5 68.1 71.1 70.1 PAV DSR .degree. C. 20.5
28.7 23.1 24.9 26.2 m-Value .degree. C. -11.6 -11.6 -13.1 -12.0
-11.6 S-Value .degree. C. -12.8 -13.0 -13.4 -13.0 -13.1 24-hour
.degree. F. 5.9 4.5 4.6 Compatibility (.degree. C.) (3.3) (2.5)
(2.5) 135.degree. C. kPa 0.783 0.833 0.855 Viscosity Response
.degree. C./% 1.60 3.05 2.60 Factor *Acid added 10 minutes prior to
crosslinker addition. **Acid added 1 hr after crosslinker
addition.
[0055] None of the PMA blends with sulfuric acid treatment were
compatible after 24 hrs. However, there was improvement in the
compatibility in Examples 10 and 11 compared to the control blend
(Example 9, Table V). Nevertheless, it is known that this asphalt
is compatible after 48 hrs with crosslinked FP502 modification.
[0056] Treatment of the neat asphalt with 0.1 wt % phosphoric acid
resulted in only modest improvement in the limiting RTFO DSR Fail
Temperature and no improvement in the ODSR Fail Temperature
(Example 12). The PAV DSR Fail Temperature was increased outside of
the specification maximum of 25.degree. C. There was no change in
the low-temperature properties. PMA produced from the phosphoric
acid-treated base showed no effective change in the ODSR Fail
Temperature (Example 13), compared to the control blend (Example 9,
Table VI), but did show a 2.4.degree. C. improvement in the
limiting RTFO DSR Fail Temperature. The results were intermediate
for the PMA in which the acid was added after crosslinking (Example
14). Test results for the blends treated with phosphoric acid are
presented in Table VI. TABLE-US-00006 TABLE VI Properties of PAR
asphalt and PMA treated with phosphoric acid. Examples Com. Com.
Com. Inv. Com. Units 7 12 9 13 14 2nd base Wt % 100 99.9 98 98 98
asphalt Phosphoric Wt % 0.1 0.1* 0.1** Acid FP502 Wt % 2 2 2 MBT Wt
% 0.06 0.06 0.06 Sulfur Wt % 0.12 0.12 0.12 Binder DSR .degree. C.
65.9 66.3 71.4 71.2 72.1 RTFO DSR .degree. C. 64.9 66.2 68.1 70.5
69.6 PAV DSR .degree. C. 20.5 27.4 23.1 25.6 25.7 m-Value .degree.
C. -11.6 -11.4 -13.1 -12.1 -12.1 S-Value .degree. C. -12.8 -11.9
-13.4 -12.9 -13.0 24-hr .degree. F. 5.9 1.2 1.3 Compatibility (3.3)
(0.6) (0.7) 135.degree. C. kPa 0.783 0.800 0.807 Viscosity Response
.degree. C./% 1.60 2.80 2.35 Factor *Acid added 10 minutes prior to
crosslinker addition. **Acid added 1 hr after crosslinker
addition.
[0057] The PMA blends with phosphoric acid treated asphalt were
rubber compatible after 24 hours. The improvement in the
high-temperature MP1 properties was greatest in the PMA blend in
which the acid was added prior to crosslinking.
[0058] The addition of about 0.1 wt % phosphoric or sulfuric acid
was thus demonstrated to increase the high-temperature limiting
RTFO DSR Fail Temperature by approximately 3.degree. C. There was
no appreciable change in the low-temperature SHRP properties.
Addition of the acid before crosslinking resulted in the greatest
improvement in high-temperature properties. Intermediate MP1
properties were negatively affected by acid addition.
[0059] In the foregoing specification, the methods and compositions
have been described with reference to specific embodiments thereof,
and have been demonstrated as effective in providing methods for
preparing asphalt and polymer compositions with improved high
temperature properties. However, it will be evident that various
modifications and changes can be made to the method without
departing from the broader spirit or scope of the invention as set
forth in the appended claims. Accordingly, the specification is to
be regarded in an illustrative rather than a restrictive sense. For
example, specific combinations or amounts of asphalt, polymer,
crosslinker, acid, activator, accelerator, and other components
falling within the claimed parameters, but not specifically
identified or tried in a particular PMA system, are anticipated and
expected to be within the scope of this innovations discussed
herein. Specifically, the method and discovery of the compositions
are expected to work with acids and crosslinkers other than those
exemplified herein.
* * * * *