U.S. patent application number 11/390643 was filed with the patent office on 2007-10-04 for industrial asphalt composition.
This patent application is currently assigned to BUILDING MATERIALS INVESTMENT CORPORATION. Invention is credited to Yonghong Ruan.
Application Number | 20070231545 11/390643 |
Document ID | / |
Family ID | 38559408 |
Filed Date | 2007-10-04 |
United States Patent
Application |
20070231545 |
Kind Code |
A1 |
Ruan; Yonghong |
October 4, 2007 |
Industrial asphalt composition
Abstract
This invention is based upon the discovery that a small amount
of lime can be incorporated into industrial asphalt to greatly
improve its resistance to oxidative hardening cracking and low
temperature thermal cracking. The incorporation of a small amount
of lime into industrial asphalt accordingly results in products
made therewith offering improved service life. For instance,
roofing shingles made with such asphalt that contains a small
amount of lime will be more resistant to cracking and failure in
both hot and cold weather climates. The subject invention more
specifically discloses an asphalt roofing shingle having an upper
surface and an underside, said asphalt roofing shingle being
comprised of a fiber mat which is coated with an asphalt
composition, wherein the upper surface of the asphalt roofing
shingle includes a layer of roofing granules, wherein the asphalt
composition has a softening point which is within the range of
185.degree. F. (85.degree. C.) to 250.degree. F. (121.degree. C.)
and a penetration value of at least 15 dmm, and wherein the asphalt
composition contains from 0.1 weight percent to 5 weight percent
lime. The subject invention further discloses a method for
preparing an industrial asphalt comprising (1) heating a base
asphalt to a temperature which is within the range of about
100.degree. F. (38.degree. C.) to 400.degree. F. (204.degree. C.)
to produce a hot base asphalt, and (2) mixing from 0.1 weight
percent to 5 weight percent lime throughout the hot base asphalt
while the mixture of hot base asphalt and lime is maintained at a
temperature which is within the range of 100.degree. F. (38.degree.
C.) to 400.degree. F. (204.degree. C.) to produce the industrial
asphalt.
Inventors: |
Ruan; Yonghong; (Wayne,
NJ) |
Correspondence
Address: |
Attn: William J. Davis, Esq.;Legal Department, Building No. 8-2
GAF MATERIALS CORPORATION
1361 Alps Road
Wayne
NY
07470
US
|
Assignee: |
BUILDING MATERIALS INVESTMENT
CORPORATION
|
Family ID: |
38559408 |
Appl. No.: |
11/390643 |
Filed: |
March 28, 2006 |
Current U.S.
Class: |
428/143 |
Current CPC
Class: |
E04D 5/02 20130101; Y10T
428/24372 20150115; E04D 1/20 20130101; C08L 95/00 20130101; E04D
2001/005 20130101; C08L 95/00 20130101; C08L 2666/72 20130101; C08L
95/00 20130101; C08L 2666/74 20130101 |
Class at
Publication: |
428/143 |
International
Class: |
E01F 9/04 20060101
E01F009/04 |
Claims
1. A method for preparing an industrial asphalt comprising (1)
heating a base asphalt to a temperature which is within the range
of about 100.degree. F. to 400.degree. F. to produce a hot base
asphalt, and (2) mixing from 0.1 weight percent to 5 weight percent
lime throughout the hot base asphalt while the mixture of hot base
asphalt and lime is maintained at a temperature which is within the
range of 100.degree. F. to 400.degree. F. to produce the industrial
asphalt.
2. A method as specified in claim 1 wherein the lime is in the form
of solid particles or a solid powder.
3. A method as specified in claim 1 wherein the lime is added to
the asphalt as an aqueous slurry.
4. A method as specified in claim 1 wherein the mixing in step (2)
is fulfilled by mechanical agitation.
5. A method as specified in claim 1 wherein the mixing in step (2)
is fulfilled by bubbling an inert gas through the hot lime modified
base asphalt.
6. A method as specified in claim 1 wherein the lime is mixed into
the asphalt in step (2) for a period of time which is within the
range of about 10 minutes to about 4 hours.
7. A method as specified in claim 1 wherein the amount of lime
added to the hot base asphalt in step (2) is within the range of
0.5 weight percent to 2 weight percent.
8. A method for preparing an industrial asphalt comprising (1)
heating a base asphalt to a temperature which is within the range
of about 100.degree. F. to 400.degree. F. to produce a hot base
asphalt, (2) adding from about 0.1 weight percent to about 5 weight
percent of a lime compound to the hot base asphalt, (3) mixing the
lime compound throughout the hot base asphalt to prepare a lime
compound containing base asphalt, (4) heating the lime compound
containing base asphalt to a temperature which is within the range
of about 400.degree. F. to about 550.degree. F. to produce a hot
lime compound containing base asphalt, (5) sparging an oxygen
containing gas through the hot lime compound containing base
asphalt for a period of time which is sufficient to produce the
industrial asphalt.
9. An industrial asphalt composition comprising asphalt and from
0.1 weight percent to 5 weight percent lime.
10. An industrial asphalt composition as specified in claim 9
wherein the lime is present in the asphalt composition at a level
which is within the range of 0.5 weight percent to about 2 weight
percent.
11. An industrial asphalt composition as specified in claim 9
wherein the asphalt has a softening point which is within the range
of 185.degree. F. to 250.degree. F., and wherein the asphalt has a
penetration value of at least 15 dmm.
12. An industrial asphalt composition as specified in claim 9
wherein the industrial asphalt has a softening point which is
within the range of 185.degree. F. to 235.degree. F. and wherein
the industrial asphalt has a penetration value which is within the
range of 15 dmm to 35 dmm.
13. An industrial asphalt composition as specified in claim 9
wherein the industrial asphalt has a softening point which is
within the range of 190.degree. F. to 220.degree. F. and wherein
the industrial asphalt has a penetration value which is within the
range of 15 dmm to 25 dmm.
14. An industrial asphalt as specified in claim 9 wherein the
industrial asphalt is a Type I asphalt which has a softening point
of from 135.degree. F. to 151.degree. F. and a penetration of from
18 dmm to 60 dmm at 77.degree. F.
15. An industrial asphalt as specified in claim 9 wherein the
industrial asphalt is a Type II asphalt which has a softening point
of from 158.degree. F. to 176.degree. F. and a penetration of from
18 dmm to 40 dmm at 77.degree. F.
16. An industrial asphalt as specified in claim 9 wherein the
industrial asphalt is a Type III asphalt which has a softening
point of from 185.degree. F. to 205.degree. F. and a penetration of
from 15 dmm to 35 dmm at 77.degree. F.
17. An industrial asphalt as specified in claim 9 wherein the
industrial asphalt is a Type IV asphalt which has a softening point
of from 210.degree. F. to 225.degree. F. and a penetration of from
12 dmm to 25 dmm at 77.degree. F.
18. An industrial asphalt composition as specified in claim 9
wherein the lime is hydrated lime.
19. An industrial asphalt as specified in claim 9 wherein the lime
compound is dolomitic normal hydrate.
20. An industrial asphalt as specified in claim 9 wherein the lime
is a dolomitic pressure hydrate.
21. An industrial asphalt as specified in claim 9 wherein the lime
is quicklime.
22. An industrial asphalt as specified in claim 9 wherein the lime
compound is a dolomitic quicklime.
23. An asphalt roofing shingle having an upper surface and an
underside, said asphalt roofing shingle being comprised of a fiber
mat which is coated with an asphalt composition, wherein the upper
surface of the asphalt roofing shingle includes a layer of roofing
granules, wherein the asphalt composition has a softening point
which is within the range of 185.degree. F. to 250.degree. F. and a
penetration value of at least 15 dmm, and wherein the asphalt
composition contains from 0.1 weight percent to 5 weight percent
lime.
24. An asphalt roofing shingle as specified in claim 23 wherein the
industrial asphalt has a softening point which is within the range
of 185.degree. F. to 235.degree. F., and wherein the industrial
asphalt has a penetration value which is within the range of 15 dmm
to 35 dmm.
25. An asphalt roofing shingle as specified in claim 23 wherein the
industrial asphalt has a softening point which is within the range
of 190.degree. F. to 220.degree. F., and wherein the industrial
asphalt has a penetration value which is within the range of 15 dmm
to 25 dmm.
26. An asphalt roofing shingle as specified in claim 23 wherein the
lime is present in the asphalt composition at a level which is
within the range of 0.5 weight percent to about 2 weight
percent.
27. An asphalt roofing shingle as specified in claim 23 wherein the
lime is hydrated lime.
28. An asphalt roofing shingle as specified in claim 23 wherein the
fiber mat is comprised of glass fibers.
29. An asphalt roofing shingle as specified in claim 23 wherein the
fiber mat is comprised of at least one polymeric fiber selected
from the group consisting of polyethylene fibers, polypropylene
fibers, polyester fibers, nylon fibers, and acrylic fibers.
30. An asphalt roofing shingle as specified in claim 23 wherein the
lime is dolomitic normal hydrate.
31. An asphalt roofing shingle as specified in claim 23 wherein the
lime is dolomitic pressure hydrate.
32. An asphalt roofing shingle as specified in claim 23 wherein the
lime is quicklime.
33. An asphalt roofing shingle as specified in claim 23 wherein the
lime is dolomitic quicklime.
34. An asphalt roll roofing membrane that is comprised of a
reinforcing mat having an upper side and a lower side wherein said
reinforcing mat is coated on its upper surface and its lower
surface with an asphalt composition that is comprised of asphalt
and from 0.1 weight percent to 5 weight percent lime.
35. A roofing underlayment which is comprised of an asphalt
saturated felt wherein the asphalt contains from 0.1 weight percent
to 5 weight percent lime.
36. A built-up roofing which is comprised of multiple layers of
roofing paper or felt that are adhered together with asphalt and
which is covered on its upper surface with mineral roofing granules
or gravel wherein the asphalt contains from 0.1 to 5 weight percent
lime.
37. An adhesive composition which is comprised of asphalt and of a
polymer modifier wherein the asphalt contains from 0.1 to 5 weight
percent lime.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to asphaltic materials which
are particularly useful in manufacturing industrial asphalt
products such as roofing shingles, roll roofing membranes, roofing
underlayment, asphalt-based adhesives, asphalt-based sealants and
built-up roofing. The present invention also relates to a method
for preparing such asphaltic materials.
BACKGROUND OF THE INVENTION
[0002] Asphalt offers outstanding binding and waterproofing
characteristics. These physical attributes of asphalt have led to
its widespread utilization in paving, roofing, and waterproofing
applications. However, with exposure to elements of the environment
such as solar radiation, high temperatures, rain, snow, etc., the
asphalt ages as a result of oxidation. With oxidation, asphalt
becomes stiffer, less ductile, and less capable of relieving
stress. When the stress in the asphalt builds to a critical limit
in excess of what it can withstand, cracking occurs. This type of
cracking which is caused mainly by asphalt oxidation or aging is
called "oxidative hardening cracking." This type of cracking is
typical and commonly experienced in the Sun Belt where asphalt can
be exposed to a grueling sun and high temperatures for an extended
period of time.
[0003] Exposure to low temperatures can also cause asphalt to
crack. Asphalt is a viscoelastic material, meaning it behaves more
like a solid at low temperatures and behaves as a liquid at high
temperatures. As a result, with drops in temperature, asphalt's
viscosity and modulus can increase significantly. In addition,
asphalt has a relatively high coefficient of thermal expansion
(CTE), and under most conditions, asphalt's CTE is higher than the
substrate to which it is applied (such as wood or metal). With
considerable temperature drops, asphalt will experience much more
contraction than its substrate. However, the substrate keeps the
asphalt from contracting freely, and as a result, stress is built
inside of the asphalt. When the stress built in asphalt exceeds the
critical value that it can withstand, cracking occurs. Cracking
caused by low temperature is called "low temperature thermal
cracking". This form of cracking mainly occurs in cold climates,
such as in the northern United States and Canada during the
winter.
[0004] Each year asphalt cracking costs various industries billions
of dollars. As a result, it is desirable to have a method to
improve the durability and service life of asphaltic materials. To
improve asphalt resistance to "oxidative hardening cracking"
asphalt has to be modified to be less susceptible to oxidative
hardening. To improve asphalt resistance to "low temperature
thermal cracking" asphalt has to have better low temperature
flexibility.
[0005] Hydrated lime, Ca(OH).sub.2, is commonly used in the paving
industry as an anti-strip agent to treat aggregate. It is believed
that hydrated lime is able to improve asphalt-aggregate interaction
(or bonding) to reduce moisture/water damage to asphalt pavement.
In this technology, a small amount of dry hydrated lime is blended
with the aggregate for a certain time period and then the treated
aggregate is mixed with hot asphalt to produce a hot
asphalt/aggregate mixture. U.S. Pat. No. 5,512,093 discloses a
process to treat aggregate with a quicklime slurry. In this process
the properties of hot mix asphalt are improved by treating the
aggregate which is combined with bituminous binder and lime. A hot
quicklime slurry is produced by slaking quicklime with water at the
site of the hot mix asphalt plant using a portable mixing tank. The
hot quicklime slurry is then applied to the aggregate. The
aggregate is dried and combined with the binder to produce the hot
mix asphalt.
[0006] U.S. Pat. No. 6,027,558 discloses a hot mix asphalt
composition in which hydrated lime is added directly to the asphalt
binder prior to the addition of the asphalt binder to the mineral
aggregate constituent of the composition. The lime-asphalt mixture
is then added to the mineral aggregate. The lime component is added
to the asphalt binder in an amount which exceeds about 10% by
weight, based upon the total weight of asphalt binder in the
composition. U.S. Pat. No. 6,027,558 also discloses an improved hot
mix asphalt paving composition, comprising: a lime-asphalt mixture
and mineral aggregate, the lime-asphalt mixture being first formed
by adding a lime component directly to an asphalt binder prior to
addition of the asphalt binder to the mineral aggregate material;
and wherein the lime component is present in the lime-asphalt
mixture in an amount which exceeds about 10% by weight, based upon
the total weight of asphalt binder.
[0007] When a relatively high level of hydrated lime (for instance,
greater than about 10%) is added to asphalt, the hydrated lime will
typically act mainly as filler. In such cases, the improvements
observed come mainly from physical asphalt-hydrated lime
interactions. High levels of lime have been incorporated into
paving asphalt compositions for decades as an antistripping
agent.
[0008] U.S. Pat. No. 6,562,118 discloses a method for the
modification of asphaltic compositions such that cellulosic fibers
are not degraded by the asphalt at elevated temperatures. This is
achieved by the addition of certain inorganic or organic alkaline
materials to the composition. The alkaline materials that can be
used are selected from the group consisting of hydroxide,
carbonates, silicates and basic salts of Group I, II and III metals
and suitable organic bases which are thermodynamically stable under
the conditions that the asphalt composition will be used.
SUMMARY OF THE INVENTION
[0009] This invention is based upon the discovery that a small
amount of lime can be incorporated into industrial asphalt to
greatly improve its resistance to oxidative hardening cracking and
low temperature thermal cracking. The incorporation of a small
amount of lime into industrial asphalt accordingly results in
products made therewith offering improved service life. For
instance, roofing shingles made with such asphalt that contains a
small amount of lime will be more resistant to cracking and failure
in both hot and cold weather climates.
[0010] In this application, a relatively low amount (0.1 to 5% by
weight based upon the weight of asphalt) of lime, preferably
hydrated lime, is added to the industrial asphalt to attain
improved properties. This improvement is believed to be a result of
the chemical interaction between the asphalt and the lime. In any
case, industrial asphalt products such as roofing shingles, roll
roofing membranes, roofing underlayment, asphalt-based adhesives,
asphalt-based sealants and built-up roofing made with such lime
treated asphalt offer improved service life under adverse
environmental conditions.
[0011] The subject invention more specifically discloses an asphalt
roofing shingle having an upper surface and an underside, said
asphalt roofing shingle being comprised of a fiber mat which is
coated with an asphalt composition, wherein the upper surface of
the asphalt roofing shingle includes a layer of roofing granules,
wherein the asphalt composition has a softening point which is
within the range of 185.degree. F. (85.degree. C.) to 250.degree.
F. (121.degree. C.) and a penetration value of at least 15 dmm, and
wherein the asphalt composition contains from 0.1 weight percent to
5 weight percent lime.
[0012] The subject invention also reveals an asphalt roll roofing
membrane that is comprised of a reinforcing mat having an upper
side and a lower side wherein said reinforcing mat is coated on its
upper surface and its lower surface with an asphalt composition
that is comprised of asphalt and from 0.1 weight percent to 5
weight percent lime.
[0013] The subject invention also reveals a roofing underlayment
which is comprised of an asphalt saturated roofing paper or an
asphalt saturated glass fiber mat wherein the asphalt contains from
0.1 weight percent to 5 weight percent lime.
[0014] The present invention further discloses a built-up roofing
which is comprised of multiple layers of roofing paper or felt that
are adhered together with asphalt and which is covered on its upper
surface with mineral roofing granules or gravel wherein the asphalt
contains from 0.1 to 5 weight percent lime.
[0015] The present invention further discloses an adhesive
composition which is comprised of asphalt and of a block copolymer
modifier wherein the asphalt contains from 0.1 to 5 weight percent
lime.
[0016] The subject invention further discloses a method for
preparing an industrial asphalt comprising (1) heating a base
asphalt to a temperature which is within the range of about
100.degree. F. (38.degree. C.) to 400.degree. F. (204.degree. C.)
to produce a hot base asphalt, and (2) mixing from 0.1 weight
percent to 5 weight percent lime throughout the hot base asphalt
while the mixture of hot base asphalt and lime is maintained at a
temperature which is within the range of 100.degree. F. (38.degree.
C.) to 400.degree. F. (204.degree. C.) to produce the industrial
asphalt.
[0017] The present invention also reveals an industrial asphalt
composition comprising asphalt and from 0.1 weight percent to 5
weight percent lime, wherein the asphalt has a softening point
which is within the range of 185.degree. F. (85.degree. C.) to
250.degree. F. (121.degree. C.), wherein the asphalt has a
penetration value of at least 15 dmm, and wherein the asphalt
composition is void of aggregate, such as small stones and crushed
rocks.
DETAILED DESCRIPTION OF THE INVENTION
[0018] The process of this invention is useful in treating asphalt
to produce industrial asphalt with improved durability. Such
industrial asphalt can be used in making articles of manufacture
having improved resistance to cracking at both low and high
temperatures. Articles made with the improved industrial asphalt of
this invention are typically more resistant to deterioration and
provide a longer useful service life. The improved industrial
asphalt made by the technique of this invention is particularly
useful in manufacturing asphalt roofing products, such as asphalt
roofing shingles. Roofing shingles made with the industrial asphalt
of this invention offer a higher level of resistance to cracking
and deterioration than do roofing shingles made with conventional
asphalt. This advantage is of particular importance in cases where
roofing shingles will be used on buildings that are located in
geographic regions that experience extremely hot and/or cold
weather conditions. In any case, roofing shingles made with the
improved industrial asphalt of this invention normally provide a
longer useful service life.
[0019] The technique of this invention can be used to improve the
crack resistance of virtually any industrial asphalt. The base
asphalt treated by the process of this invention is normally the
petroleum residue from a vacuum distillation column used in
refining crude oil. The asphaltic material used as the starting
material can also be air blown asphalt, solvent extracted asphalt,
naturally occurring asphalt, or synthetic asphalt. Blends of such
asphaltic materials can also be treated by the process of this
invention. The asphalt flux can also include polymers, recycled
tire rubber, recycled engine oil residue, recycled plastics,
softeners, antifungal agents, biocides (algae inhibiting agents),
and other additives. Tar and pitch can also be used as the starting
material for treatment by the technique of this invention.
[0020] The industrial asphalt that is used in manufacturing roofing
shingles will normally have a softening point which is within the
range of 185.degree. F. (85.degree. C.) to 250.degree. F.
(121.degree. C.) and a penetration value of at least 15 dmm.
Preferably, industrial asphalt that is used in making roofing
shingles will have a softening point which is within the range of
185.degree. F. (85.degree. C.) to 235.degree. F. (113.degree. C.),
and a penetration value which is within the range of 15 dmm to 35
dmm. Finally, industrial asphalt employed in manufacturing roofing
shingles will more preferably have a softening point which is
within the range of 190.degree. F. (88.degree. C.) to 220.degree.
F. (104.degree. C.) and a penetration value which is within the
range of 15 dmm to 25 dmm.
[0021] For purposes of this invention, asphalt softening points are
measured following ASTM D 36-95 "Standard Test Method for Softening
Point of Bitumen (Ring-and Ball Apparatus)" and asphalt
penetrations are measured following ASTM D 5-97 "Standard Test
Method for Penetration of Bituminous Materials".
[0022] In other embodiments of this invention the asphalt can be
(1) a Type I asphalt which has a softening point of from
135.degree. F. (57.degree. C.) to 151.degree. F. (66.degree. C.)
and a penetration of from 18 dmm to 60 dmm at 77.degree. F.
(25.degree. C.), (2) a Type II asphalt which has a softening point
of from 158.degree. F. (70.degree. C.) to 176.degree. F.
(80.degree. C.) and a penetration of from 18 dmm to 40 dmm at
77.degree. F. (25.degree. C.), (3) a Type III asphalt which has a
softening point of from 185.degree. F. (85.degree. C.) to
205.degree. F. (96.degree. C.) and a penetration of from 15 dmm to
35 dmm at 77.degree. F. (25.degree. C.), or (4) a Type IV asphalt
which has a softening point of from 210.degree. F. (99.degree. C.)
to 225.degree. F. (107.degree. C.) and a penetration of from 12 dmm
to 25 dmm at 77.degree. F. (25.degree. C.).
[0023] The asphalt treated by the technique of this invention can
be air blown to attain the desired softening point. In such an air
blowing procedure the asphalt is heated to a temperature which is
within the range of 400.degree. F. (204.degree. C.) to 550.degree.
F. (288.degree. C.) and an oxygen containing gas is blown (sparged)
through it. This air blowing step will preferably be conducted at a
temperature which is within the range of 425.degree. F.
(218.degree. C.) to 525.degree. F. (274.degree. C.) and will most
preferably be conducted at a temperature which is within the range
of 450.degree. F. (232.degree. C.) to 500.degree. F. (260.degree.
C.). This air blowing step will typically take about 2 hours to
about 8 hours and will more typically take about 3 hours to about 6
hours. However, the air blowing step will be conducted for a period
of time that is sufficient to attain the ultimate desired softening
point and penetration value. In making industrial asphalt for
roofing shingles the asphalt will typically be air blown until a
softening point which is within the range of 185.degree. F.
(85.degree. C.) to 250.degree. F. (121.degree. C.) and a
penetration value of at least 15 dmm is attained.
[0024] The oxygen containing gas (oxidizing gas) used in such an
air blowing step is typically air. The air can contain moisture and
can optionally be enriched to contain a higher level of oxygen.
Chlorine enriched air or pure oxygen can also be utilized in the
air blowing step. Air blow can be performed either with or without
a conventional air blowing catalyst. Some representative examples
of air blowing catalysts include ferric chloride (FeCl.sub.3),
phosphorous pentoxide (P.sub.2O.sub.5), aluminum chloride
(AlCl.sub.3), boric acid (H.sub.3BO.sub.3), copper sulfate
(CuSO.sub.4), zinc chloride (ZnCl.sub.2), phosphorous sesquesulfide
(P.sub.4S.sub.3), phosphorous pentasulfide (P.sub.2S.sub.5), phytic
acid (C.sub.6H.sub.6[OPO--(OH).sub.2].sub.6), and organic sulfonic
acids.
[0025] The asphalt treatment process of this invention is conducted
by first heating the asphalt being treated to a temperature which
is within the range of about 100.degree. F. (38.degree. C.) to
400.degree. F. (204.degree. C.) to produce a hot base asphalt. Then
from about 0.1 weight percent to about 5 weight percent lime,
preferably hydrated lime, is mixed throughout the hot base asphalt
while it is maintained at a temperature which is within the range
of 100.degree. F. (38.degree. C.) to 400.degree. F. (204.degree.
C.) to produce the industrial asphalt. In most cases this mixing
step will be conducted over a time period which is within the range
of about 10 minutes to about 4 hours. The lime will typically be
mixed into the asphalt over a period of about 20 minutes to 2
hours. Typically about 0.5 weight percent to about 4 weight percent
of the lime will be added to the hot base asphalt. It is generally
preferred to mix 1 weight percent to 3 weight percent of the lime
into the base asphalt.
[0026] For purposed of this invention "lime" refers to compounds
that include at least one of following functional components: (1)
quicklime (CaO); (2) calcium hydroxide (Ca(OH).sub.2); (3)
dolomitic quicklime (CaO.MgO); (4) dolomitic normal hydrate
(Ca(OH).sub.2.MgO); (5) dolomitic pressure hydrate
(Ca(OH).sub.2.Mg(OH).sub.2); and (6) mixtures of any or all of
these functional components. It is preferred for the lime to be
hydrated lime.
[0027] In the practice of this invention it may be advantageous to
add the lime to the base asphalt at the end of the air blow
procedure while the blown asphalt is still hot. By adding the lime
to the hot asphalt at the end of the air blowing step it is not
necessary to heat the asphalt from ambient temperature to the
required mixing temperature. This can save energy because the lime
is added to the base asphalt after it is being cooled from the
temperature used in the air blowing procedure. The lime can
optionally be mixed into the base asphalt in the vessel used for
the air blowing in which case agitation can be provided by
continuing to blow air or some other gas into the asphalt being
treated to homogeneously disperse the lime through it. After the
lime is dispersed throughout the asphalt it is, of course, cooled
to ambient temperature to produce the improved industrial asphalt
of this invention.
[0028] The improved industrial asphalt of this invention can be
used in making roofing products and other industrial products using
standard procedures. For instance, the industrial asphalt can be
blended with fillers (such as, limestone, stonedust, sand, mica,
slate flour, diatorriaceous earth and the like), stabilizers,
polymers, recycled tire rubber, recycled engine oil residue,
recycled plastics, softeners, antifungal agents, biocides (algae
inhibiting agents), and other additives. The filler can optionally
be a glass filler, such as chopped glass fibers.
[0029] Asphalt roofing shingles can be made by coating a fiber mat
with the improved industrial asphalt composition of this invention
and subsequently applying a layer of roofing granules to the upper
surface thereof to produce the roofing shingle. This is normally
accomplished by (1) unwinding a roll of fiber roofing mat, (2)
coating the fiber roofing mat with the industrial asphalt of this
invention which has been heated to an elevated temperature while
the fiber roofing mat is being unwound, (3) applying mineral
roofing granules to the asphalt-covered surface of the mat and
embedding the granules in the hot asphalt to form a single-layer
sheet of shingle material, (4) cooling the sheet of shingle
material to ambient temperature, and (5) cutting the sheet of
shingle material into roofing shingles of the desired size and
shape.
[0030] The fiber roofing mat will typically be comprised of an
inorganic fiber, such as a glass fiber. For instance, the fiber
roofing mat can be comprised of a polysiloxane compound having
--[SiO]-- repeating units. However, the fiber roofing mat can
optionally be comprised of one or more organic polymeric fibers,
such as polyethylene, polypropylene, polyester, nylon, or acrylic
fibers. On the other hand, the fiber roofing mat can be void of
organic fibers, such as cellulosic fibers (wood or pulp
particles).
[0031] In cases where the fiber roofing mat is comprised of a
polysiloxane it can be modified with various substituents which
include linear, branched, or aromatic end-groups. Such end groups
can optionally contain oxygen, sulfur and/or nitrogen. Generally,
the polysiloxanes are classified as polyalkyl-silanes,
polyaryl-silanes, polyalkylaryl-silanes, and polyether-siloxanes.
The polysiloxanes that are typically the most useful have a weight
average molecular weight (MW) of at least 600. A preferred class of
polysiloxanes is polydialkylsiloxanes, with polydimethylsiloxane
being highly preferred.
[0032] Some representative examples of suitable polysiloxanes that
can be employed in the fiber roofing mats employed in making the
asphalt roofing shingles of this invention include, but are not
limited to, polyalkylene oxide-modified
polydimethylsiloxane-dimethylsiloxane copolymer (MW=13,000);
polyalkylene oxide-modified polydimethylsiloxane-dimethylsiloxane
copolymer (MW=3000); polyalkylene oxide-modified
polydimethylsiloxane-dimethylsiloxane copolymer (MW=4000);
(carboxylatepropyl)methylsiloxane-dimethylsiloxane copolymer
(MW>1000); dimethylsiloxane-(60% PO-40% EO) block copolymer
(MW=20,000); (hydroxyalkyl functional)
methylsiloxane-dimethylsiloxane copolymer (MW=5000);
aminopropylmethylsiloxane-dimethylsiloxane copolymer MW=4500);
aminoethylaminopropylmethoxysiloxane-dimethylsiloxane copolymer
(MW>1000); glycidoxy propyl dimethoxy silyl end-blocked dimethyl
siloxane polymer (MW=5000); methacryloxy propyl dimethyoxy silyl
dimethyl siloxane polymer (MW=40,000); vinyl dimethoxy silyl
end-blocked dimethyl siloxane polymer (MW=6500);
aminoethylaminopropyl dimethoxy silyl end-blocked dimethyl siloxane
polymer (MW=3800); amine-alkyl modified methylalkylaryl silicone
polymer (MW=7800); epoxy functional dimethylpolysiloxane copolymer
(MW=8300); dimethylpolysiloxane (MW=26,439);
dodecylmethylsiloxane-hydroxypolyalkyleneoxypropyl methylsiloxane
copolymer (MW=1900);
(dodecylmethylsiloxane)-(2-phenylpropylmethylsiloxane) copolymer
(MW>1000) and polyalkylene oxide-modified
polydimethylsiloxane-dimethylsiloxane copolymer (MW=600).
[0033] U.S. Pat. No. 6,737,369 discloses coated fiber roofing mats
that can be utilized in the practice of this invention. These
cured, non-woven roofing mats are comprised of a mixture of fibers
having different fiber lengths which are fixedly distributed in a
binder, wherein the fibers contain a polysiloxane compound. The
mixture of fibers used in these fiber mats contain from about 0
weight percent to about 100 weight percent fibers having an average
length of from about 0.5 mm to about 60 mm and from about 0 weight
percent to about 100 weight percent fibers having an average length
of from about 10 mm to about 150 mm. More preferably, from about 20
weight percent to about 80 weight percent of the fibers will have
an average length of from about 10 mm to about 45 mm and from about
20 weight percent to about 80 weight percent of fibers having an
average length of from about 30 mm to about 80 mm. The fibers
having differing fiber lengths typically have an average diameter
of from about 1 .mu.m to about 100 .mu.m, with an average diameter
of from about 5 .mu.m to about 25 .mu.m being more highly
preferred. Such fibers can be obtained from commercial sources or
made by techniques well known to those skilled in the art. The
binders that can be used in making such fiber roofing mats are
described in detail in U.S. Pat. No. 6,737,369 and the teachings of
U.S. Pat. No. 6,737,369 are incorporated herein by reference in
their entirety.
[0034] Virtually any type of conventional roofing granules can be
used in making the asphalt shingles of this invention. For
instance, the roofing granules can be comprised of greenstone,
nephylene syenite, common gravel slate, gannister, quartzite,
greystone, and the like. The roofing granules used will typically
be of a size that is within the range of about 420 micrometers to
1680 micrometers (40 mesh to 12 mesh). However, the use of larger
or smaller granules is within the scope of this invention. For
aesthetic purposes the roofing granules will typically be colored.
In many cases two or more different colors of roofing granules will
be mixed to attain the desired color for the roofing shingle.
Colored roofing granules can be prepared by first preheating
mineral rock granules having a size of about 420 micrometers to
about 1680 micrometers (40 to 12 US mesh) to a temperature which is
within the range of 100.degree. F. (38.degree. C.) to 1000.degree.
F. (538.degree. C.). Then, a paint slurry containing a pigment is
applied to the heated granules in a mixer. The color coated
granules are subsequently heated in a kiln to a temperature of
about 350.degree. F. (175.degree. C.) to 1200.degree. F.
(650.degree. C.). Then, the colored granules are cooled and passed
to a post-treatment stage where the colored granules are treated
with an oil formulation in a rotary mixer. The oil formulation is
applied to reduce dust and promote adhesion of the granules to the
asphalt substrate. After the oil treatment, the granules are
removed from the post-treatment stage, transported, and
subsequently applied to the asphalt substrate. U.S. Pat. No.
5,286,544 discloses a specific process for preparing colored
roofing granules that involves treating the granules with a
composition that contains an oil and an elastomeric rubber that is
compatible with the oil. The teaching of U.S. Pat. No. 5,286,544
are incorporated herein by reference with respect to types of
roofing granules that can be utilized in the practice of this
invention and with respect to techniques for making such roofing
granules.
[0035] U.S. Pat. No. 4,717,614 and U.S. Pat. No. 5,860,263 describe
asphalt roofing shingles that can be made utilizing the improved
industrial asphalt compositions of this invention as well as
techniques for manufacturing such roofing shingles. The teachings
of both U.S. Pat. No. 4,717,614 and U.S. Pat. No. 5,860,263 are
incorporated herein by reference in their entirety.
[0036] Asphalt roll roofing membranes can be made by coating a
reinforcing mat on both its upper surface and its lower surface
with the improved industrial asphalt composition of this invention.
The reinforcing mat will typically be a non-woven mat that is
comprised of a polymeric material, such as polyester, which has the
ability to stretch under tension. This is important so that the
asphalt roll roofing will be flexible enough to withstand normal
roof movement as well as expansion and contraction over the
temperature range experienced in the geographic region where the
asphalt roll roofing is installed. Typically, the improved
industrial asphalt composition of this invention will also contain
a polymeric modifier to provide the asphalt with an ability to
stretch when used in such applications. The polymer modifier will
typically be a rubbery polymer and can optionally be a block
copolymer such as a styrene-butadiene-styrene block copolymer. The
asphalt roll roofing will also preferably be coated on its upper
surface with roofing granules such as those that can be used in
making roofing shingles.
[0037] Roofing underlayment can be made with the improved
industrial asphalt of this invention by using such asphalt to
saturate roofing paper or fiber mat.
[0038] Built-up roofing can be made with the improved industrial
asphalt of this invention by using such asphalt to adhere multiple
layers of roofing paper or felt together in manufacturing the
built-up roofing material. The built-up roofing will typically be
covered on its upper surface with roofing granules or gravel.
[0039] The improved industrial asphalt of this invention can also
be used in manufacturing asphalt based adhesive compositions and
asphalt based sealant compositions. This can be done by simply
substituting the improved industrial asphalt of this invention for
the conventional asphalts that are conventionally used in making
asphalt based adhesives and asphalt based sealant compositions.
Such compositions will typically also include one or more
elastomeric materials, such as ground rubber from used tires. Such
sealant and adhesive compositions can also contain one or more
synthetic rubbers, natural rubber, or an elastomeric block
copolymer, such as a styrene-butadiene-styrene block copolymer.
[0040] This invention is illustrated by the following examples that
are merely for the purpose of illustration and are not to be
regarded as limiting the scope of the invention or the manner in
which it can be practiced. Unless specifically indicated otherwise,
parts and percentages are given by weight.
1. Durability Improvement
[0041] In this invention, asphalt durability (weathering
resistance) is defined as the cycle-to-failure in a weather-o-meter
according to ASTM D 4798-00 "Standard Test Method for Accelerated
Weathering Test Method Conditions and Procedures for Bituminous
Materials (Xeon-Arc Method)" Cycle A. Asphalt failure is determined
according to ASTM D 1670.
COMPARATIVE EXAMPLE 1 AND WORKING EXAMPLE 2
[0042] The base asphalt 1 utilized in Comparative Example 1 was
tested and determined to have a durability of 34 cycles. This
asphalt was not treated in accordance with the technique of this
invention.
[0043] In Working Example 2 the same asphalt that was tested in
Comparative Example 1 (asphalt 1) was treated with mixing hydrated
lime into it at a temperature of 300.degree. F. (149.degree. C.)
with the mixing being conducted over a period of about 0.5 hours.
The asphalt made by this procedure was subsequently tested for
durability and was determined to have a durability of 60 cycles.
This experiment accordingly shows that the durability of base
asphalt can be improved by treating it with hydrated lime at an
elevated temperature.
[0044] The results attained in this series of experiments at a
Ca(OH).sub.2 level of 0 weight percent and 2 weight percent are
summarized in Table 1. TABLE-US-00001 TABLE 1 Ca(OH).sub.2 Example
Composition (weight %) Durability (cycles) 1 Asphalt 1 0 34 2 Lime
Modified Asphalt 1 2 60
COMPARATIVE EXAMPLE 3 AND WORKING EXAMPLE 4
[0045] In this series of experiments a second base asphalt sample
(asphalt 2) was treated in accordance with the method of this
invention and compared to a control. The base asphalt 2 tested in
Comparative Example 3 was determined to have a durability of 46
cycles. In Working Example 4 hydrated lime was mixed into the base
asphalt at a temperature of 300.degree. F. (149.degree. C.) over a
period of 0.5 hours. The hydrated lime modified asphalt 2 prepared
in Working Example 4 was determined to have a durability of 74
cycles. This experiment again shows that the durability of base
asphalt can be improved by treating it with hydrated lime.
[0046] The results attained in this series of experiments at a
Ca(OH).sub.2 level of 0 weight percent and 2 weight percent are
summarized in Table 2. TABLE-US-00002 TABLE 2 Ca(OH).sub.2 Example
Composition (weight %) Durability (cycles) 3 Asphalt 2 0 46 4 Lime
Modified Asphalt 2 2 74
COMPARATIVE EXAMPLE 5 AND WORKING EXAMPLE 6
[0047] In this series of experiments a second base asphalt sample
(asphalt 3) was treated in accordance with the method of this
invention and compared to a control. The base asphalt 3 tested in
Comparative Example 5 was determined to have a durability of 46
cycles. In Working Example 6 hydrated lime was mixed into the base
asphalt at a temperature of 300.degree. F. (149.degree. C.) over a
period of 0.5 hours. The hydrated lime modified asphalt 3 prepared
in Working Example 6 was determined to have a durability of 74
cycles. This experiment again shows that the durability of base
asphalt can be improved by treating it with hydrated lime.
[0048] The results attained in this series of experiments at a
Ca(OH).sub.2 level of 0 weight percent and 2 weight percent are
summarized in Table 3. TABLE-US-00003 TABLE 3 Ca(OH).sub.2 Example
Composition (weight %) Durability (cycles) 5 Asphalt 3 0 46 6 Lime
Modified Asphalt 3 2 74
2. Low Temperature Flexibility Improvement
EXAMPLE 7
[0049] In this experiment the asphalt samples of Comparative
Example 5 and Working Example 6 were evaluated to determine their
low temperature flexibility. Modulus data was obtained from a
dynamic mechanic analyzer (DMA) at different temperatures. At a
fixed temperature, as the modulus of the asphalt increases its
stiffness also increases and its flexibility decreases. In other
words, lower modulus is indicative of better flexibility. In
Working Example 6 where the asphalt 3 was modified with 2% hydrated
lime (based on the asphalt weight), there is significant drop in
modulus, meaning the modified asphalt had better flexibility at low
temperature than did the control asphalt. For example, at
-20.degree. C., asphalt 3 had a modulus of 852.8 MPa, and the
modified asphalt 3 has a modulus of 634.2 MPa, which shows a
reduction of 218.6 MPa in modulus. In other words, the lime
modified asphalt 3 exhibited a better resistance to "low
temperature thermal cracking" than the control asphalt.
[0050] The modulus of the control and the lime modified asphalt
over a range of different temperatures is reported in Table 4.
TABLE-US-00004 TABLE 4 Modulus (MPa) Asphalt 3 + Modulus reduction
Temperature (.degree. C.) Asphalt 3 2% Ca(OH).sub.2 (MPa) -40 1056
931.3 124.7 -30 1019 837.9 181.1 -20 852.8 634.2 218.6 -10 565.1
397.4 167.7 0 328 231.9 96.1 10 175.7 119.6 56.1 20 90.82 60.35
30.5 30 45.36 28.48 16.9
3. Oxidative Hardening Resistance Improvement
EXAMPLE 8
[0051] In this experiment a lime modified asphalt composition was
made and compared to a control that was not modified with lime. In
this procedure, 2 weight percent hydrated lime was mixed into
asphalt 4 in the working example. The control asphalt (asphalt 4)
and the 2% hydrated lime modified asphalt 4 were subjected to
weathering in a weather-o-meter for 10 days according to ASTM D
4798-00 "Standard Test Method for Accelerated Weathering Test
Method Conditions and Procedures for Bituminous Materials (Xeon-Arc
Method)" Cycle A. The results of this experiment are reported in
Table 5. TABLE-US-00005 TABLE 5 Angular frequency Aging index
(radian/sec) Asphalt 4 Asphalt 4 + 2% Ca(OH).sub.2 0.6283 40.6 25.5
1.354 36.0 23.8 2.914 28.0 20.3 6.283 23.6 19.1 13.52 19.7 17.0
29.11 16.8 14.6 62.46 14.4 12.9 134.7 12.2 11.3 292.4 10.2 9.5
434.4 9.7 9.1
[0052] Aging index was defined as the ratio of modulus of
weather-o-meter aged asphalt to modulus of unaged asphalt: Aging
index=modulus of weather-o-meter aged asphalt/modulus of unaged
asphalt
[0053] Modulus was measured on a dynamic shear rheometer (DSR) at
76.degree. C. at different angular frequencies.
[0054] Data indicates that there is a significant drop in aging
index with hydrated lime modification especially at low angular
frequency, meaning the addition of hydrated lime into asphalt can
significantly reduce the rate of asphalt aging or oxidation. In
other words, an addition of a small amount of hydrated lime, into
asphalt can dramatically increase asphalt's resistance to
"oxidative hardening cracking".
[0055] While certain representative embodiments and details have
been shown for the purpose of illustrating the subject invention,
it will be apparent to those skilled in this art that various
changes and modifications can be made therein without departing
from the scope of the subject invention.
* * * * *