U.S. patent application number 11/558711 was filed with the patent office on 2007-08-30 for bitumen composition.
Invention is credited to David Bobee, Sylvie Claude Lebigre, Alain Marcel Bernard Seive.
Application Number | 20070199476 11/558711 |
Document ID | / |
Family ID | 35985223 |
Filed Date | 2007-08-30 |
United States Patent
Application |
20070199476 |
Kind Code |
A1 |
Bobee; David ; et
al. |
August 30, 2007 |
BITUMEN COMPOSITION
Abstract
A novel bitumen composition comprising a paraffin wax, wherein
the wax has a congealing point of between 85 and 120.degree. C. and
a PEN at 43.degree. C., expressed in 0.1 mm, as determined by IP
376 of more than 5.
Inventors: |
Bobee; David; (Petit
Couronne, FR) ; Lebigre; Sylvie Claude;
(Petit-Couronne, FR) ; Seive; Alain Marcel Bernard;
(Petit Couronne, FR) |
Correspondence
Address: |
SHELL OIL COMPANY
P O BOX 2463
HOUSTON
TX
772522463
US
|
Family ID: |
35985223 |
Appl. No.: |
11/558711 |
Filed: |
November 10, 2006 |
Current U.S.
Class: |
106/275 ;
106/273.1 |
Current CPC
Class: |
C08L 95/00 20130101;
C08L 91/08 20130101; C08L 91/06 20130101; C08L 95/00 20130101 |
Class at
Publication: |
106/275 ;
106/273.1 |
International
Class: |
C08L 95/00 20060101
C08L095/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 10, 2005 |
EP |
05292400.8 |
Claims
1. A bitumen composition comprising a paraffin wax, wherein the wax
has a congealing point of between 85 and 120.degree. C. and a PEN
at 43.degree. C., expressed in 0.1 mm, as determined by IP 376 of
more than 5.
2. A bitumen composition according to claim 1, wherein the paraffin
wax has a PEN at 43.degree. C. as determined by IP 376 of more than
7.
3. A bitumen composition according to claim 1, wherein the paraffin
wax has a PEN at 43.degree. C. as determined by IP 376 of below
350.
4. A bitumen composition according to claim 3, wherein the paraffin
wax has a PEN at 43.degree. C. as determined by IP 376 of below
70.
5. A bitumen composition according to claim 1, wherein the bitumen
component has a penetration in the range of 1 to 450 mm/10, a
softening point from 30 to 130.degree. C., a penetration index
between +9 and -3 and a viscosity at 60.degree. C. between 10 to
20,000 Pas.
6. A bitumen composition according to claim 1, wherein the content
of the paraffin wax is between 0.5 and 10 wt %.
7. A bitumen composition according to claim 1, wherein the paraffin
wax is obtained by a process comprising the steps of (a)
hydrocracking/hydroisomerisating a Fischer-Tropsch product, (b)
performing one or more distillate separations on the effluent of
step (a) to obtain a middle distillate fuel fraction and a soft
paraffin wax additive having an initial boiling point of between
500 and 600.degree. C.
8. A bitumen composition according to claim 7 wherein the wax as
obtained in said process is blended with a normal paraffin wax
fraction having a congealing point of between 90 and 120.degree. C.
as isolated by distillation from the Fischer-Tropsch product.
9. An asphalt composition comprising aggregates and between 1 and
20 wt % of the bitumen composition according to claim 1.
10. An asphalt composition according to claim 9, wherein the
paraffin wax has a PEN at 43.degree. C. as determined by IP 376 of
more than 7.
11. An asphalt composition according to claim 9, wherein the
paraffin wax has a PEN at 43.degree. C. as determined by IP 376 of
below 350.
12. An asphalt composition according to claim 11, wherein the
paraffin wax has a PEN at 43.degree. C. as determined by IP 376 of
below 70.
13. An asphalt composition according to claim 9, wherein the
bitumen component has a penetration in the range of 1 to 450 mm/10,
a softening point from 30 to 130.degree. C., a penetration index
between +9 and -3 and a viscosity at 60.degree. C. between 10 to
20,000 Pas.
14. An asphalt composition according to claim 9, wherein the
content of the paraffin wax is between 0.5 and 10 wt %.
15. An asphalt composition according to claim 9, wherein the
paraffin wax is obtained by a process comprising the steps of (a)
hydrocracking/hydroisomerisating a Fischer-Tropsch product, (b)
performing one or more distillate separations on the effluent of
step (a) to obtain a middle distillate fuel fraction and a soft
paraffin wax additive having an initial boiling point of between
500 and 600.degree. C.
16. An asphalt composition according to claim 15 wherein the wax as
obtained in said process is blended with a normal paraffin wax
fraction having a congealing point of between 90 and 120.degree. C.
as isolated by distillation from the Fischer-Tropsch product.
17. A road surface comprising the asphalt composition of claim
9.
18. A paraffin wax having a congealing point of between 85 and
120.degree. C. and a PEN at 43.degree. C., expressed in 0.1 mm, as
determined by IP 376 of more than 5 in suitable form for use as a
bitumen additive.
19. A process to lower the Fraass point of a bitumen composition
comprising adding to a bitumen composition a paraffin wax having a
congealing point of between 85 and 120.degree. C. and a PEN at
43.degree. C., expressed in 0.1 mm, as determined by IP 376 of more
than 5.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of European Patent
Application No. 05292400.8, filed Nov. 10, 2005, which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention is directed to a bitumen composition
comprising a paraffin wax additive. The invention is also directed
to the paraffin wax additive itself.
BACKGROUND OF THE INVENTION
[0003] Bitumen compositions are widely applied as road surfaces for
motor vehicles and airplanes. These compositions are also referred
to as asphalt and comprise bitumen and aggregates such as sand,
gravel, grit or the like. Additives are widely applied to improve
certain properties of the bitumen composition for use as road
surfaces.
[0004] U.S. Pat. No. 6,588,974, WO-A-0216499 and AU-B-200137219
disclose a bitumen composition containing a Fischer-Tropsch
paraffin (FT paraffin) as an additive. According to U.S. Pat. No.
6,588,974 the Fischer-Tropsch paraffin additive is a mixture of
more than 90% n-alkanes and the remainder being iso-alkanes. An
advantage of adding the FT paraffin additive is that the additive
lowers the viscosity of the bitumen composition at elevated, e.g.
135 and 180.degree. C, temperatures. This is advantageous because
this is the temperature at which the bitumen mixture is used when
making road surfaces. In other words the additive improves the
workability of the bitumen composition.
[0005] According to these publications the FT paraffin has a chain
length of between 30 and 100 carbon atoms. AU-B-200137219
exemplifies a commercially available Fischer-Tropsch paraffin
additive as SASOBIT (SASOBIT is a Registered Trademark). According
to the product specifications dated Nov. 11, 2003 for SASOBIT, the
congealing range according to DIN-ISO 02207 is .ltoreq.99.degree.
C. as published by Sasol Wax GmbH, Hamburg.
[0006] A problem encountered by the addition of the FT paraffin wax
additives is that the Fraass point remains the same or even
increases when the content of additives increases. The Fraass point
(EN12593) is indicative for the brittleness of the bitumen mixture
at low temperatures. In this test a sample of bituminous binder is
applied on a metal plate. This plate is submitted to a constant
cooling rate and flexed repeatedly until the binder layer breaks.
The temperature at which the first crack appears is reported as the
Fraass breaking point. A low Fraass point is for example desirable
when road surfaces are made in areas having a cold climate.
SUMMARY OF THE INVENTION
[0007] Applicants have now discovered that the Fraass point can be
lowered when a slightly isomerized paraffin wax is used instead of
a highly normal paraffin wax. Applicants have further found that
the viscosity at elevated temperatures is lowered comparable to
when using the state of the art normal paraffin FT paraffin
additive.
[0008] The invention is therefore directed to a bitumen composition
comprising a paraffin wax having a congealing point of between 85
and 120.degree. C. and a PEN at 43.degree. C., expressed in 0.1 mm,
as determined by IP 376 of more than 5.
[0009] The invention is also directed to a paraffin wax having a
congealing point of between 85 and 120.degree. C. and a PEN at
43.degree. C., expressed in 0.1 mm, as determined by IP 376 of more
than 5 mm in suitable form for use as a bitumen additive. This
additive will also be referred to in this application as a soft
paraffin wax additive.
[0010] The invention is also directed to a process to lower the
Fraass point of a bitumen composition by adding to a bitumen
composition a paraffin wax having a congealing point of between 85
and 120.degree. C., as determined by ISO 2207, and a PEN at
43.degree. C., expressed in 0.1 mm, as determined by IP 376 of more
than 5.
DETAILED DESCRIPTION
[0011] The soft paraffin wax additive of the present invention has
a congealing point of between 85 and 120.degree. C. and a PEN at
43.degree. C., expressed in 0.1 mm, as determined by IP 376 of more
than 5. Preferably the congealing point of the above wax is above
90.degree. C.
[0012] The soft paraffin wax additive having generally the
combination of said congealing point and PEN values is constituted
for a major portion of iso-paraffins. The quantity of iso-paraffins
is however difficult to quantify in this boiling range. For this
reason these more easily quantifiable properties are used.
[0013] In order to reduce the Fraass temperature significantly, it
is preferred to use a soft wax having a PEN at 43.degree. C.
expressed in 0.1 mm of greater than 7, more preferably greater than
8 and even more preferably greater than 10. The PEN at 43.degree.
C. is preferably below 350. If one desires to achieve both an
increase in softening point according to EN1427 and a reduction in
Fraass temperature, the PEN at 43.degree. C. is preferably between
5 and 70, more preferably between 7 and 70. The TBC-GLC recovery at
450.degree. C. is preferably less than 2 wt %, more preferably less
than 1 wt %. The softness of the wax can be influenced by adjusting
the process conditions of the manufacturing process and/or by
blending soft wax and hard wax, wherein the hard wax can be a more
normal paraffinic wax such as for example SASOBIT or the Sarawax
SX100 or Sarawax SX105 type wax products as obtainable from Shell
MDS Malaysia Sdn Bhd.
[0014] Suitable bitumens include those with penetrations in the
range of 1 to 450 mm/10 as determined in accordance with EN 1426.
The softening point of suitable bitumens may range from 30 to
130.degree. C., preferably, 40 to 100.degree. C. as determined in
accordance with EN 1427. The penetration index of suitable bitumens
may range between +9 and -3. The viscosity at 60.degree. C. may be
10 to 20,000 Pas.
[0015] The content of soft paraffin wax additive in the bitumen
composition according to the invention may be up to 20 wt %, more
preferably between 0.1 to 20 wt %, even more preferably between 0.5
to 10 wt %. When the partly isomerized paraffin wax is used, the
Fraass temperature decreases, even at higher contents of said
partly isomerized paraffin wax. When the substantially normal
paraffin wax, like for example the commercial SASOBIT product, is
used in a high content, the Fraass temperature does not improve
with respect to the starting bitumen.
[0016] The soft paraffin wax additive may be blended with the
bitumen using any suitable method. For instance, the additive may
be added in divided form, for example as pellets or as a powder or
in a molten state, to the bitumen. The bitumen may be in the molten
state, which is at a temperature sufficient to dissolve or disperse
the additive. Suitable temperatures range between 120 and
230.degree. C., preferably, 130 and 190.degree. C.
[0017] It may be possible to add sufficient additive to the bitumen
to produce a wax/bitumen blend of the desired final concentration.
In certain applications, however, it may be desirable to produce a
concentrated blend or "masterbatch" of the additive and bitumen,
which may be mixed with additive-free bitumens or bitumen having a
low additive concentration to produce blends of the desired final
composition. Suitably, the masterbatch may comprise the additive in
a concentration of 10 to 30 wt %.
[0018] The bitumen composition according to the invention may be
employed as a binder for aggregates to form an asphalt composition.
The aggregates employed in such compositions include conventional
aggregates such as granite. Optionally, fillers of, for example,
limestone and cellulose may also be included in the bituminous
composition. Sand and dust may also be present.
[0019] Other additives may also be present with the soft paraffin
wax additive. Examples of possible other additives are polymers
such as elastomers, for example styrene-butadiene co-polymer,
styrene-butadiene-styrene copolymer; plastomers, for example
ethylene vinyl acetate co-polymer, poly ethylene and combinations
of said polymers, reactive polymers, for example reactive ethylene
ter polymer, acrylate copolymers, cross-linking agents, for example
sulphur and sulphur containing compounds, adhesion dopes and IP
booster, for example polyphosphoric acid.
[0020] When the bitumen composition according the invention is
employed as a binder with aggregates, the bitumen composition may
form 1 to 20 wt %, preferably, 2 to 15 wt %, more preferably, 4 to
10 wt %, and most preferably, 4 to 7 wt % of the overall asphalt
composition. The aggregate content of the overall composition may
be more than 50 wt %, preferably, more than 60 wt %, even more
preferably, more than 70 wt % for example, 75 to 90 wt %. The
remainder of the asphalt composition may comprise sand, cellulose
and/or limestone.
[0021] When preparing the asphalt composition, it may be possible
to add the soft paraffin wax additive to the bitumen, in the
presence of the aggregates and/or fillers. It may also be possible
to mix the additive with the bitumen prior to the addition of
aggregate and/or filler. An example of a possible method of adding
the soft paraffin wax additive is described in AU-B-200137219.
[0022] Asphalt compositions as described above may be used as
pavings and coverings for a variety of surfaces, particularly, for
example, lorry parks, motorway road surfacing, air fields,
residential roads, service station forecourts, car parks, taxi-ways
and driveways. The bitumen composition may also be beneficially
used in so-called top layers and sub layers as accordance with the
teaching of U.S. Pat. No. 6,588,974 for normal paraffin wax
containing bitumen compositions, which reference is incorporated by
reference.
[0023] The bitumen composition according to the present invention
may also be used as part of so-called joint sealants, which are for
example used to fix concrete elements in airport surfaces, or as
part of a roofing felt composition.
[0024] The soft paraffin wax additive is preferably obtained by
hydroisomerization of the substantially linear paraffin wax as
obtained in a Fischer-Tropsch process. The wax having the required
congealing point may be isolated by distillation from the
hydroisomerized product or alternatively the feed to the
hydroisomerization is so chosen that the soft wax additive is
directly obtained from the hydroisomerized product. The properties
of the wax additive as obtained in said hydroisomerization can be
suitably modified by blending the wax as obtained by said
hydroisomerization and FT paraffin comprising more than 90%
n-alkanes. Examples of the latter are the afore mentioned SASOBIT,
Paraflint H1 and Sarawax SX100 and Sarawax SX105. Paraflint H1 is
obtainable from Sasol-Moore and Munger. The Sarawax products are
obtainable from Shell MDS Malaysia Sdn Bhd. Applicants found that
by using a blend of the FT normal paraffin and the soft paraffin
wax additive,a bitumen composition can be obtained wherein the
Fraass temperature is lowered and the high temperature properties
are improved. Preferably the congealing point and the PEN at
43.degree. C. of such a blended wax has the properties as described
above.
[0025] Examples of the Fischer-Tropsch synthesis and routes to this
soft wax additive are described in WO-A-02102941, EP-A-1498469,
WO-A-2004009739 and EP-A-1268712.
[0026] Applicants found that a very suitable soft paraffin wax can
be obtained as a by-product of the following process wherein middle
distillates are prepared from a Fischer-Tropsch wax. This process
comprises the steps of (a) hydrocracking/hydroisomerisating a
Fischer-Tropsch product, (b) performing one or more distillate
separations on the effluent of step (a) to obtain a middle
distillate fuel fraction and a soft paraffin wax additive having an
initial boiling point of between 500 and 600.degree. C. The
additive is preferably obtained as a residual fraction in a vacuum
distillation step. The PEN value at 43.degree. C. of the wax as
obtained by this process may be reduced if required by blending
this wax with a wax fraction isolated by distillation from the
starting Fischer-Tropsch product. This fraction, preferably
hydrogenated in order to remove oxygenates and olefins and having a
congealing point of between 90 and 120.degree. C., is a
substantially normal paraffin wax having a lower PEN value at
43.degree. C. By blending this component with the softer wax a
controlled value for the PEN at 43.degree. C. may be obtained.
[0027] In order to obtain a wax additive product having the desired
PEN and congealing point in combination with a commercially
attractive yield of the middle distillate main product it has been
found that it is advantageous to start from a relatively heavy
Fischer-Tropsch product. The relatively heavy Fischer-Tropsch
product has suitably at least 30 wt %, preferably at least 50 wt %,
and more preferably at least 55 wt % of compounds having at least
30 carbon atoms. Furthermore the weight ratio of compounds having
at least 60 or more carbon atoms and compounds having at least 30
carbon atoms of the Fischer-Tropsch product is suitably at least
0.2, preferably at least 0.4 and more preferably at least 0.55.
Preferably the Fischer-Tropsch product comprises a C.sub.20+
fraction having an ASF-alpha value (Anderson-Schulz-Flory chain
growth factor) of at least 0.925, preferably at least 0.935, more
preferably at least 0.945, even more preferably at least 0.955.
[0028] The initial boiling point of the Fischer-Tropsch product as
feed to step (a) may range up to 400.degree. C., but is preferably
below 200.degree. C. Preferably any compounds having 4 or less
carbon atoms and any compounds having a boiling point in that range
are separated from a Fischer-Tropsch synthesis product before the
Fischer-Tropsch synthesis product is used in step (a). In addition
to the Fischer-Tropsch product, other fractions may be processed in
step (a). Possible other fractions may suitably be any excess
microcrystalline wax as obtained in step (b).
[0029] Such a Fischer-Tropsch product can be obtained by any
process, which yields a relatively heavy Fischer-Tropsch product.
Not all Fischer-Tropsch processes yield such a heavy product. An
example of a suitable Fischer-Tropsch process is described in
WO-A-9934917. These processes may yield a Fischer-Tropsch product
as described above.
[0030] The Fischer-Tropsch product will contain no or very little
sulphur and nitrogen containing compounds. This is typical for a
product derived from a Fischer-Tropsch reaction, which uses
synthesis gas containing almost no impurities. Sulphur and nitrogen
levels will generally be below the detection limits, which are
currently 5 ppm for sulphur and 1 ppm for nitrogen. The soft
paraffin wax additive will consequently also have such low sulphur
and nitrogen levels. The process conditions and other directions of
how to perform the above process have been reported earlier by
applicant in WO-A-2004009739 which publication is hereby
incorporated by reference.
[0031] The soft wax as obtained from one of the above
Fischer-Tropsch processes is suitably transformed into a form in
which handling of the product is facilitated. Suitable forms are
containers filled with solid wax product, which containers can be
heated at the location of use and wherein the wax is added to the
bitumen in its liquid state. Heated containers containing the wax
in its liquid state may also be used. The wax may also be provided
as pellets, extrudates, flakes or powder. In order to prevent the
wax particles from sticking to each other, silica powder and the
like may be added to provide a less sticky surface of the wax
particles.
[0032] The invention will be illustrated with the following
non-limiting examples.
EXAMPLE 1
[0033] To a 35/50 pen grade bitumen having the properties as listed
in Table 2, 1.5, 3 and 6 wt % of a soft paraffin wax additive
having the properties as listed in Table 1 have been added. Mixing
was performed at 160.degree. C. The soft paraffin wax was made
according to the principles of Example 1 of WO-A-2004/009739.
[0034] The viscosity at 135, 150 and 170.degree. C. and the Fraass
point of the resulting mixtures were measured. The results are
listed in Table 3.
EXAMPLE 2
[0035] Example 1 was repeated using a 70/100 pen grade bitumen
having the properties listed in Table 2. The viscosity at 135, 150
and 170.degree. C. and the Fraass point of the resulting mixtures
were measured. The results are listed in Table 4.
Comparative Experiment A
[0036] Example 1 was repeated using SASOBIT having the properties
as listed in Table 1. The viscosity at 135, 150 and 170.degree. C.
and the Fraass point of the resulting mixtures were measured. The
results are listed in Table 3.
Comparative Experiment B
[0037] Example 2 was repeated using SASOBIT having the properties
as listed in Table 1. The viscosity at 135, 150 and 170.degree. C.
and the Fraass point of the resulting mixtures were measured. The
results are listed in Table 4.
EXAMPLE 3
[0038] To the 35/50 pen grade bitumen of Example 16 wt % of a 50/50
wt % blend of the soft wax additive and the SASOBIT (see Table 1)
were added. The PEN at 43.degree. C. (0.1 mm) of the resulting wax
blend was 39.
[0039] The increase in softening point relative to the starting
bitumen was 24.6.degree. C. and the decrease in Fraass temperature
relative to the starting bitumen was 2.degree. C.
[0040] Table 3 and Table 4 show that at a given concentration and
for a given bitumen, the additive of the invention leads to the
lowest Fraass breaking point values for the corresponding
bituminous blend when compared to the unmodified and the SASOBIT
modified bitumen.
[0041] These Tables also show that the additive of the invention
reduces the viscosity at a given temperature of the corresponding
bitumen blends when compared to the un-modified bitumen.
TABLE-US-00001 TABLE 1 Soft paraffin SASOBIT wax additive
Congealing point (ISO 2207) (.degree. C.) 100 97 Initial boiling
point (.degree. C.) TBC-GLC 470 434 TBC-GLC recovery at 450.degree.
C. (wt %) 0 0.6 TBC-GLC recovery at 500.degree. C. (wt %) 1.1 1 PEN
at 43.degree. C. (0.1 mm) 3 >250 (*) (*) the PEN at 43.degree.
C. (0.1 mm) for similar soft wax products obtainable via the same
process was 317 as expressed in 0.1 mm.
[0042] TABLE-US-00002 TABLE 2 Bitumen PEN at 25.degree. C.
Softening point properties (dmm) (EN1426) (.degree. C.) (EN1427) PI
(pen25/sft) 35/50 pen grade 41 52 -1.15 70/100 pen grade 84 46.4
-0.87
[0043] TABLE-US-00003 TABLE 3 Additive Viscosity Viscosity
Viscosity content at 135.degree. C. at 150.degree. C. at
170.degree. C. Fraass (wt %) (Pa s) (Pa s) (Pa s) (.degree. C.)
Bitumen of 0 0.43 0.22 0.10 -7 Example 1 and A Example 1 1.5 0.4
0.2 0.09 -13 A 1.5 0.39 0.2 0.09 -7 Example 1 3 0.35 0.18 0.08 -11
A 3 0.36 0.18 0.08 -7 Example 1 6 0.29 0.15 0.07 -15 A 6 0.22 0.12
0.06 -6
[0044] TABLE-US-00004 TABLE 4 Additive Viscosity Viscosity
Viscosity content at 135.degree. C. at 150.degree. C. at
170.degree. C. Fraass (wt %) (Pa s) (Pa s) (Pa s) (.degree. C.)
Bitumen of 0 0.25 0.13 0.06 -15 Example 2 and B Example 2 1.5 0.24
0.13 0.06 -19 B 1.5 0.24 0.12 0.06 -12 Example 2 3 0.22 0.11 0.05
-16 B 3 0.21 0.11 0.05 -10 Example 2 6 0.18 0.1 0.05 -25 B 6 0.17
0.1 0.05 -10
* * * * *