U.S. patent application number 12/031290 was filed with the patent office on 2009-08-20 for core-shell flow improver.
This patent application is currently assigned to CONOCOPHILLIPS COMPANY. Invention is credited to Timothy L. Burden, Wayne R. Dreher, William F. Harris, Ray L. Johnston, Wolfgang Klesse, Stuart N. Milligan, Gerold Schmitt, Kenneth W. Smith, John Wey.
Application Number | 20090209679 12/031290 |
Document ID | / |
Family ID | 40280702 |
Filed Date | 2009-08-20 |
United States Patent
Application |
20090209679 |
Kind Code |
A1 |
Dreher; Wayne R. ; et
al. |
August 20, 2009 |
CORE-SHELL FLOW IMPROVER
Abstract
A flow improver comprising a plurality of core-shell particles
that can be formed by emulsion polymerization. The core of the
core-shell particles can include a drag reducing polymer, while the
shell of the particles can include repeat units of a hydrophobic
compound and an amphiphilic compound. The flow improver can
demonstrate increased pumping stability over conventionally
prepared latex flow improvers.
Inventors: |
Dreher; Wayne R.; (Ponca
City, OK) ; Smith; Kenneth W.; (Tonkawa, OK) ;
Milligan; Stuart N.; (Ponca City, OK) ; Burden;
Timothy L.; (Ponca City, OK) ; Harris; William
F.; (Ponca City, OK) ; Johnston; Ray L.;
(Ponca City, OK) ; Klesse; Wolfgang; (Mainz,
DE) ; Schmitt; Gerold; (Aschaffenburg, DE) ;
Wey; John; (East Brunswick, NJ) |
Correspondence
Address: |
ConocoPhillips Company - IP Services Group;Attention: DOCKETING
600 N. Dairy Ashford, Bldg. MA-1135
Houston
TX
77079
US
|
Assignee: |
CONOCOPHILLIPS COMPANY
Houston
TX
|
Family ID: |
40280702 |
Appl. No.: |
12/031290 |
Filed: |
February 14, 2008 |
Current U.S.
Class: |
523/175 ;
526/258; 526/265; 526/271; 526/303.1; 526/319; 526/321; 526/332;
526/341; 526/344; 526/348 |
Current CPC
Class: |
C08L 51/003 20130101;
F17D 1/17 20130101; C08F 265/04 20130101; C08F 2/002 20130101; C08F
2/22 20130101; C08F 265/06 20130101; C08L 51/003 20130101; C08L
2666/02 20130101 |
Class at
Publication: |
523/175 ;
526/319; 526/332; 526/348; 526/321; 526/258; 526/344; 526/265;
526/341; 526/271; 526/303.1 |
International
Class: |
B05D 5/08 20060101
B05D005/08; C08F 118/02 20060101 C08F118/02; C08F 16/12 20060101
C08F016/12; C08F 210/00 20060101 C08F210/00; C08F 222/10 20060101
C08F222/10; C08F 226/06 20060101 C08F226/06; C08F 14/06 20060101
C08F014/06; C08F 20/44 20060101 C08F020/44; C08F 222/04 20060101
C08F222/04; C08F 222/38 20060101 C08F222/38 |
Claims
1. A flow improver comprising: solid particles having a polymeric
core and a polymeric shell at least partly surrounding said core,
wherein said core comprises a drag reducing polymer, wherein said
shell comprises a shell copolymer having repeat units of a
hydrophobic compound and repeat units of a first amphiphilic
compound.
2. The flow improver of claim 1, wherein said core and said shell
are formed by emulsion polymerization.
3. The flow improver of claim 1, wherein said hydrophobic compound
is selected from the group consisting of: ##STR00012## wherein
R.sub.1 is H or a C.sub.1-C.sub.10 alkyl radical, and R.sub.2 is H,
a C.sub.1-C.sub.30 alkyl radical, a C.sub.5-C.sub.30 substituted or
unsubstituted cycloalkyl radical, a C.sub.6-C.sub.20 substituted or
unsubstituted aryl radical, an aryl-substituted C.sub.1-C.sub.10
alkyl radical, a --(CH.sub.2CH.sub.2O).sub.x--R.sub.A or
--(CH.sub.2CH(CH.sub.3)O).sub.x--R.sub.A radical wherein x is in
the range of from 1 to 50 and R.sub.A is H, a C.sub.1-C.sub.30
alkyl radical, or a C.sub.6-C.sub.30 alkylaryl radical;
R.sub.3-arene-R.sub.4 (B) wherein arene is a phenyl, naphthyl,
anthracenyl, or phenanthrenyl, R.sub.3 is CH.dbd.CH.sub.2 or
CH.sub.3--C.dbd.CH.sub.2, and R.sub.4 is H, a C.sub.1-C.sub.30
alkyl radical, a C.sub.5-C.sub.30 substituted or unsubstituted
cycloalkyl radical, Cl, SO.sub.3, OR.sub.B, or COOR.sub.C, wherein
R.sub.B is H, a C.sub.1-C.sub.30 alkyl radical, a C.sub.5-C.sub.30
substituted or unsubstituted cycloalkyl radical, a C.sub.6-C.sub.20
substituted or unsubstituted aryl radical, or an aryl-substituted
C.sub.1-C.sub.10 alkyl radical, and wherein R.sub.C is H, a
C.sub.1-C.sub.30 alkyl radical, a C.sub.3-C.sub.30 substituted or
unsubstituted cycloalkyl radical, a C.sub.6-C.sub.70 substituted or
unsubstituted aryl radical, or an aryl-substituted C.sub.1-C.sub.10
alkyl radical; ##STR00013## wherein R.sub.5 is H, a
C.sub.1-C.sub.30 alkyl radical, or a C.sub.6-C.sub.20 substituted
or unsubstituted aryl radical; ##STR00014## wherein R.sub.6 is H, a
C.sub.1-C.sub.30 alkyl radical, or a C.sub.6-C.sub.20 substituted
or unsubstituted aryl radical; ##STR00015## wherein R.sub.7 is H or
a C.sub.1-C.sub.18 alkyl radical, and R.sub.8 is H, a
C.sub.1-C.sub.18 alkyl radical, or Cl; ##STR00016## wherein R.sub.9
and R.sub.10 are independently H, a C.sub.1-C.sub.30 alkyl radical,
a C.sub.6-C.sub.10 substituted or unsubstituted aryl radical, a
C.sub.5-C.sub.30 substituted or unsubstituted cycloalkyl radical,
or heterocyclic radicals; ##STR00017## wherein R.sub.11 and
R.sub.12 are independently H, a C.sub.1-C.sub.30 alkyl radical, a
C.sub.6-C.sub.20 substituted or unsubstituted aryl radical, a
C.sub.5-C.sub.30 substituted or unsubstituted cycloalkyl radical,
or heterocyclic radicals: ##STR00018## wherein R.sub.13 and
R.sub.14 are independently H, a C.sub.1-C.sub.30 alkyl radical, a
C.sub.6-C.sub.20 substituted or unsubstituted aryl radical, a
C.sub.5-C.sub.30 substituted or unsubstituted cycloalkyl radical,
or heterocyclic radicals: ##STR00019## wherein R.sub.15 is H, a
C.sub.1-C.sub.30 alkyl radical, a C.sub.6-C.sub.20 substituted or
unsubstituted aryl radical, a C.sub.5-C.sub.30 substituted or
unsubstituted cycloalkyl radical, or heterocyclic radicals;
##STR00020## wherein R.sub.16 is H, a C.sub.1-C.sub.30 alkyl
radical, or a C.sub.6-C.sub.20 aryl radical; ##STR00021## wherein
R.sub.17 and R.sub.18 are independently H, a C.sub.1-C.sub.30 alkyl
radical, a C.sub.6-C.sub.10 substituted or unsubstituted aryl
radical, a C.sub.5-C.sub.30 substituted or unsubstituted cycloalkyl
radical, or heterocyclic radicals; and ##STR00022## wherein
R.sub.19 and R.sub.20 are independently H, a C.sub.1-C.sub.30 alkyl
radical, a C.sub.6-C.sub.20 substituted or unsubstituted aryl
radical, a C.sub.5-C.sub.30 substituted or unsubstituted cycloalkyl
radical, or heterocyclic radicals.
4. The flow improver of claim 1, wherein said first amphiphilic
compound is a polymerizable surfactant, wherein the weight ratio of
repeat units of said hydrophobic compound to repeat units of said
first amphiphilic compound in said shell copolymer is in the range
of from about 0.5:1 to about 40:1.
5. The flow improver of claim 4, wherein said hydrophobic compound
comprises an acrylate and/or methacrylate.
6. The flow improver of claim 1, wherein said first amphiphilic
compound is polyethylene glycol methacrylate and/or said
hydrophobic compound is 2-ethylhexyl methacrylate.
7. The flow improver of claim 1, wherein said shell copolymer
further comprises repeat units of a second amphiphilic compound,
wherein said first amphiphilic compound is a non-ionic
polymerizable surfactant and said second amphiphilic compound is an
ionic polymerizable surfactant, wherein the weight ratio of repeat
units of said first amphiphilic compound to repeat units of said
second amphiphilic compound in said shell copolymer is in the range
of from about 0.25:1 to about 30:1.
8. The flow improver of claim 1, wherein at least 90 weight percent
of said solid particles have a particle size greater than 25
nanometers and at least 90 weight percent of said solid particles
have a particle size less than 500 nanometers, wherein the average
thickness of said shell is in the range of from about 0.1 to about
20 percent of the average particle diameter of said solid
particles.
9. The flow improver of claim 1, wherein said flow improver is in
the form of a latex comprising said solid particles dispersed in a
liquid continuous phase, wherein said latex comprises said solid
particles in an amount in the range of from about 10 to about 60
weight percent.
10. A latex flow improver comprising: an aqueous continuous phase
and a plurality of polymeric particles dispersed in said continuous
phase, wherein said polymeric particles comprise a core and a shell
at least partly surrounding said core, wherein said core comprises
a drag reducing polymer formed by emulsion polymerization, wherein
said shell is formed around said core by emulsion polymerizing at
least one hydrophobic monomer and at least one polymerizable
surfactant in the presence of said core.
11. The flow improver of claim 10, wherein said shell comprises
repeat units of said hydrophobic monomer in an amount in the range
of from about 25 to about 98 weight percent.
12. The flow improver of claim 11, wherein said hydrophobic monomer
is a methacrylate or acrylate monomer.
13. The flow improver of claim 11, wherein the emulsion
polymerization carried out to form said shell includes the use of a
first non-ionic polymerizable surfactant and a second ionic
polymerizable surfactant, wherein said shell comprises repeat units
of said first polymerizable surfactant in an amount in the range of
from about 2 to about 50 weight percent and repeat units of said
second polymerizable surfactant in an amount in the range of from
about 0.05 to about 30 weight percent.
14. The flow improver of claim 10, wherein said polymeric particles
have an average particle size less than about 1 micron, wherein the
average thickness of said shell is in the range of from about 0.5
to about 30 nanometers.
15. A process for making a flow improver comprising: (a) forming a
plurality of core particles of a drag reducing polymer by emulsion
polymerization; and (b) forming shells around at least a portion of
said core particles by emulsion polymerization to thereby produce a
plurality of core-shell particles.
16. The process of claim 15, wherein said emulsion polymerization
of step (a) is carried out in a first reaction mixture comprising a
first liquid continuous phase, wherein said emulsion polymerization
of step (b) is carried out in a second reaction mixture comprising
a second liquid continuous phase and at least a portion of said
core particles, wherein said second liquid continuous phase
comprises at least a portion of said first liquid continuous
phase.
17. The process of claim 16, wherein said second liquid continuous
phase comprises substantially all of said first liquid continuous
phase.
18. The process of claim 15, wherein said forming of step (b)
includes polymerizing one or more shell-forming monomers and at
least one polymerizable surfactant so that said shell comprises
repeat units of said shell-forming monomer and repeat units of said
at least one polymerizable surfactant.
19. The process of claim 18, wherein said shell-forming monomers
comprise an acrylate and/or methacrylate monomer.
20. The process of claim 18, wherein said shell-forming monomers
and said polymerizable surfactant do not chemically react with said
core particles during said forming of step (b).
21. The process of claim 15, wherein said shells comprise repeat
units of a hydrophobic monomer, a non-ionic polymerizable
surfactant, and an ionic polymerizable surfactant, wherein the
weight ratio of repeat units of said hydrophobic monomer to repeat
units of said non-ionic polymerizable surfactant in said shells is
in the range of from about 0.5:1 to about 40:1, wherein the weight
ratio of repeat units of said non-ionic polymerizable surfactant to
repeat units of said ionic polymerizable surfactant in said shells
is in the range of from about 0.25:1 to about 30:1.
27. A process for reducing pressure loss associated with the
turbulent flow of a fluid through a conduit, said process
comprising: using a pump to inject a latex flow improver into said
fluid flowing through said conduit, wherein said flow improver
comprises solid particles having a polymeric core and a polymeric
shell at least partly surrounding said core, wherein said core
comprises a drag reducing polymer, wherein said shell comprises a
shell copolymer having repeat units of a hydrophobic compound and
repeat units of a first amphiphilic compound.
23. The process of claim 22, wherein said solid particles have a
mean particle size of less than 1 micron, wherein said shell has a
thickness in the range of from about 0.5 to about 30
nanometers.
24. The process of claim 22, wherein said shell further comprises
repeat units of a second amphiphilic compound, wherein said first
amphiphilic compound is a non-ionic polymerizable surfactant and
said second amphiphilic compound is an ionic polymerizable
surfactant, wherein the weight ratio of repeat units of said first
polymerizable surfactant to repeat units of said second
polymerizable surfactant in said shell is in the range of from
about 0.25:1 to about 30:1.
25. The process of claim 42, wherein said pump injects said flow
improver at a pressure of at least 500 psig, wherein said flow
improver is injected into said fluid at a rate sufficient to
provide in the range of from about 0.1 to about 200 ppmw of said
drag reducing polymer in said fluid, wherein said fluid is a
hydrocarbon-containing fluid.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to flow improving
compositions. In another aspect, the present invention relates to
flow improvers comprising a plurality of polymeric core-shell
particles.
[0003] 2. Description of the Prior Art
[0004] In general, fluids transported via pipeline experience a
reduction in fluid pressure over the length of the pipeline due to
frictional energy losses. This problem is particularly evident in
pipelines spanning long distances, such as those transporting crude
oil and other liquid hydrocarbon products. In part, these
frictional losses are caused by the formation of turbulent eddies
within the fluid. To overcome these losses, pipelines employ one or
more pumps to increase the pressure of the fluid and achieve a
desired fluid flow rate through the pipe. As demand for fluids
transported via pipeline (e.g., crude oil and refined products such
as gasoline and diesel) increases, the flow rate and,
correspondingly, the pipeline pumping pressure must increase.
However design limitations (e.g., size and pressure rating) often
limit throughput of existing pipelines and building new or
upgrading existing pipelines is often very labor-intensive and
expensive.
[0005] One common solution for increasing the fluid throughput of a
pipeline without altering its pressure is to employ a flow
improving composition (i.e., a flow improver). Typically, flow
improvers comprise one or more drag reducing agents (i.e., drag
reducers) that are capable of reducing the friction losses by
suppressing eddy formation. As a result, higher fluid flow rates
are achievable at a constant pumping pressure. Typically, the drag
reducers employed in flow improving compositions comprise
ultra-high molecular weight polymers. Polymeric drag reducing
agents can be particularly advantageous for use in
hydrocarbon-containing fluids.
[0006] In general, polymeric drag reducers can be produced
according to several polymerization techniques, such as bulk
polymerization, emulsion polymerization, interfacial
polymerization, suspension polymerization, and/or rotating disk or
coacervation processes. Consequently, the resulting flow improver
can take a variety of physical forms, including, for example,
slurries, gels, emulsions, colloids, and solutions.
[0007] Colloidal (i.e., latex) flow improvers are one example of
flow improvers comprising polymeric drag reducing particles.
Typically, latex flow improvers are introduced into pipelines used
for transporting hydrocarbon-containing liquids via a high pressure
injection pump. As the latex flow improver passes through the
internals of the injection pump, at least a portion of the
surfactant molecules associated with the polymeric latex particles
can be sheared off, exposing the surface of the polymer and causing
the latex particles to agglomerate. As a result, a polymeric film
forms on internals of the pump and on downstream process equipment
(e.g., valves, pipe, etc.), thereby causing a reduction in the
pipeline system's efficiency. As the pipeline efficiency
diminishes, the system operating and maintenance costs increase,
while pipeline throughput declines.
SUMMARY OF THE INVENTION
[0008] In one embodiment of the present invention, there is
provided a flow improver comprising solid particles having a
polymeric core and a polymeric shell at least partly surrounding
the core. The core comprises a drag reducing polymer, while the
shell comprises a shell copolymer having repeat units of a
hydrophobic compound and repeat units of an amphiphilic
compound.
[0009] In another embodiment of the present invention, there is
provided a latex flow improver comprising an aqueous continuous
phase and a plurality of polymeric particles dispersed in the
continuous phase. The polymeric particles comprise a core and a
shell at least partly surrounding the core. The core comprises a
drag reducing polymer formed by emulsion polymerization. The shell
is formed around the core by emulsion polymerizing at least one
hydrophobic monomer and at least one polymerizable surfactant in
the presence of the core.
[0010] In yet another embodiment of the present invention, there is
provided a process for making a flow improver comprising: (a)
forming a plurality of core particles of a drag reducing polymer by
emulsion polymerization; and (b) forming shells around at least a
portion of the core particles by emulsion polymerization to thereby
produce a plurality of core-shell particles.
[0011] In still another embodiment of the present invention, there
is provided a process for reducing pressure loss associated with
the turbulent flow of a fluid through a conduit. The process
comprises using a pump to inject a flow improver into the fluid
flowing through the conduit, where the flow improver comprises
solid particles having a polymeric core and a polymeric shell at
least partly surrounding the core. The core of the solid particles
comprises a drag reducing polymer, while the shell comprises a
shell copolymer having repeat units of a hydrophobic compound and
repeat units of an amphiphilic compound.
BRIEF DESCRIPTION OF THE FIGURES
[0012] FIG. 1 is a schematic diagram of a test apparatus for
determining the pumping stability of various flow improvers;
[0013] FIG. 2 is a mass flow rate versus time plot resulting from a
pumping stability test performed with the apparatus depicted in
FIG. 1 using a comparative latex flow improver; and
[0014] FIG. 3 is a mass flow rate versus time plot resulting from a
pumping stability test performed with the apparatus depicted in
FIG. 1 using an inventive latex flow improver.
DETAILED DESCRIPTION
[0015] According to one embodiment of the present invention, a
composition capable of reducing pressure drop associated with
turbulent fluid flow through a conduit (i.e., a flow improving
composition or flow improver) is provided. The flow improver can
comprise a latex composition including a plurality of solid
particles dispersed in a liquid continuous phase (i.e., a latex
flow improver). In one embodiment, the dispersed solids can
comprise core-shell particles formed via a two-step emulsion
polymerization process described in detail below. The resulting
core-shell latex flow improver can have a greater pumping stability
than conventional latex flow improvers.
[0016] The first step in producing core-shell latex flow improvers
according to one embodiment of the present invention is to
synthesize the cores of the polymeric particles (i.e., the core
particles) via a first emulsion polymerization step. Generally, the
first emulsion polymerization step involves polymerizing one or
more monomers in a first reaction mixture comprising a liquid
continuous phase, at least one emulsion stabilizer, an initiation
system, and, optionally, a buffer and/or a hydrate inhibitor.
[0017] The monomer(s) employed in the first emulsion polymerization
step form core particles comprising repeating units of the
monomer(s) residues. In one embodiment, the monomer(s) employed in
the first emulsion polymerization step includes one or more
monomers selected from the group consisting of:
##STR00001##
wherein R.sub.1 is H or a C.sub.1-C.sub.10 alkyl radical, and
R.sub.7 is H, a C.sub.1-C.sub.30 alkyl radical, a C.sub.5-C.sub.30
substituted or unsubstituted cycloalkyl radical, a C.sub.6-C.sub.20
substituted or unsubstituted aryl radical, an aryl-substituted
C.sub.1-C.sub.10 alkyl radical, a
--(CH.sub.2CH.sub.2O).sub.x--R.sub.A or
--CH.sub.2CH(CH.sub.3)O).sub.x--R.sub.A radical wherein x is in the
range of from 1 to 50 and R.sub.A is H, a C.sub.1-C.sub.30 alkyl
radical, or a C.sub.6-C.sub.30 alkylaryl radical;
R.sub.3-arene-R.sub.4 (B)
wherein arene is a phenyl, naphthyl, anthracenyl, or phenanthrenyl,
R.sub.3 is CH.dbd.CH.sub.2 or CH.sub.3--C.dbd.CH.sub.2, and R is H,
a C.sub.1-C.sub.30 alkyl radical, a C.sub.5-C.sub.30 substituted or
unsubstituted cycloalkyl radical, Cl, SO.sub.3, OR.sub.B, or
COOR.sub.C, wherein R.sub.B is H, a C.sub.1-C.sub.30 alkyl radical,
a C.sub.5-C.sub.30 substituted or unsubstituted cycloalkyl radical,
a C.sub.6-C.sub.20 substituted or unsubstituted aryl radical, or an
aryl-substituted C.sub.1-C.sub.10 alkyl radical, and wherein
R.sub.C is H, a C.sub.1-C.sub.30 alkyl radical, a C.sub.5-C.sub.30
substituted or unsubstituted cycloalkyl radical, a C.sub.6-C.sub.20
substituted or unsubstituted aryl radical, or an aryl-substituted
C.sub.1-C.sub.10 alkyl radical;
##STR00002##
wherein R.sub.5 is H, a C.sub.1-C.sub.30 alkyl radical, or a
C.sub.6-C.sub.20 substituted or unsubstituted aryl radical;
##STR00003##
wherein R.sub.6 is H, a C.sub.1-C.sub.30 alkyl radical, or a
C.sub.6-C.sub.20 substituted or unsubstituted aryl radical;
##STR00004##
wherein R.sub.7 is H or a C.sub.1-C.sub.18 alkyl radical, and
R.sub.9 is H, a C.sub.1-C.sub.18 alkyl radical, or Cl;
##STR00005##
wherein R.sub.9 and R.sub.10 are independently H, a
C.sub.1-C.sub.30 alkyl radical, a C.sub.6-C.sub.20 substituted or
unsubstituted aryl radical, a C.sub.5-C.sub.30 substituted or
unsubstituted cycloalkyl radical, or heterocyclic radicals;
##STR00006##
wherein R.sub.11 and R.sub.12 are independently H, a
C.sub.1-C.sub.30 alkyl radical, a C.sub.6-C.sub.20 substituted or
unsubstituted aryl radical, a C.sub.5-C.sub.30 substituted or
unsubstituted cycloalkyl radical, or heterocyclic radicals;
##STR00007##
wherein R.sub.13 and R.sub.14 are independently H, a
C.sub.1-C.sub.30 alkyl radical, a C.sub.6-C.sub.20 substituted or
unsubstituted aryl radical, a C.sub.5-C.sub.30 substituted or
unsubstituted cycloalkyl radical, or heterocyclic radicals;
##STR00008##
wherein R.sub.15 is H, a C.sub.1-C.sub.30 alkyl radical, a
C.sub.6-C.sub.20 substituted or unsubstituted aryl radical a
C.sub.5-C.sub.30 substituted or unsubstituted cycloalkyl radical,
or heterocyclic radicals;
##STR00009##
wherein R.sub.16 is H, a C.sub.1-C.sub.30 alkyl radical, or a
C.sub.6-C.sub.20 aryl radical;
##STR00010##
wherein R.sub.17 and R.sub.18 are independently H, a
C.sub.1-C.sub.30 alkyl radical, a C.sub.6-C.sub.20 substituted or
unsubstituted aryl radical, a C.sub.5-C.sub.30 substituted or
unsubstituted cycloalkyl radical, or heterocyclic radicals; and
##STR00011##
wherein R.sub.19 and R.sub.20 are independently H, a
C.sub.1-C.sub.30 alkyl radical, a C.sub.6-C.sub.20 substituted or
unsubstituted aryl radical, a C.sub.5-C.sub.30 substituted or
unsubstituted cycloalkyl radical, or heterocyclic radicals.
[0018] In one embodiment, an acrylate or methacrylate monomer
(e.g., 2-ethylhexyl methacrylate) can be employed as the monomer(s)
of the first emulsion polymerization step. Further, the monomer(s)
employed can exclude alpha olefius (i.e., the monomer(s) can be all
non-alpha-olefiu(s)."). Generally, the first reaction mixture of
the first polymerization step can comprise the monomer(s) in an
amount in the range of from about 10 to about 60, about 20 to about
55, or 30 to 50 weight percent.
[0019] The liquid continuous phase of the first reaction mixture
can comprise a polar liquid. Examples of polar liquids can include,
but are not limited to, water, organic liquids such as alcohols and
diols, and mixtures thereof. According to one embodiment, the first
reaction mixture can comprise the liquid continuous phase in an
amount in the range of from about 20 to about 80, about 35 to about
75, or 50 to 70 weight percent.
[0020] The emulsion stabilizing compound(s) (i.e., emulsion
stabilizer) can be added to the first reaction mixture so that the
first reaction mixture comprises in the range of from about 0.1 to
about 10, about 0.25 to about 6, or 0.5 to 4 weight percent of an
emulsion stabilizer. In one embodiment, the emulsion stabilizer can
comprise a surfactant. In general, surfactants suitable for use in
the reaction mixture of the first emulsion polymerization step can
include at least one high HLB anionic or non-ionic surfactant. The
term "HLB number" refers to the hydrophile-lipophile balance of a
surfactant in an emulsion. The HLB number is determined by the
methods described by W. C. Griffin in J. Soc. Cosmet. Chem. 1, 311
(1949) and J. Soc. Cosmet. Chem., 5, 249 (1954), which are
incorporated herein by reference. In one embodiment, the HLB number
of surfactants for use with forming the reaction mixture for the
first polymerization step can be at least about 8, at least about
10, or at least 12.
[0021] Exemplary high HLB anionic surfactants include, but are not
limited to, high HLB alkyl sulfates, alkyl ether sulfates, dialkyl
sulfosuccinates, alkyl phosphates, alkyl aryl sulfonates, and
sarcosinates. Suitable examples of commercially available high HLB
anionic surfactants include, but are not limited to, sodium lauryl
sulfate (available as RHODAPON LSB from Rhodia Incorporated,
Cranbury, N.J.), dioctyl sodium sulfosuccinate (available as
AEROSOL.RTM. OT from Cytec Industries, Inc., West Paterson, N.J.),
2-ethylhexyl polyphosphate sodium salt (available from Jarchem
Industries Inc., Newark, N.J.), sodium dodecylbenzene sulfonate
(available as NORFOX.RTM. 40 from Norman, Fox & Co., Vernon,
Calif.), and sodium lauroylsarcosinic (available as HAMPOSYL L-30
from Hampshire Chemical Corp., Lexington, Mass.).
[0022] Exemplary high HLB non-ionic surfactants include, but are
not limited to, high HLB sorbitan esters. PEG fatty acid esters,
ethoxylated glycerine esters, ethoxylated fatty amines, ethoxylated
sorbitan esters, block ethylene oxide/propylene oxide surfactants,
alcohol/fatty acid esters, ethoxylated alcohols, ethoxylated fatty
acids, alkoxylated castor oils, glycerine esters, linear alcohol
ethoxylates, and alkyl phenol ethoxylates. Suitable examples of
commercially available high HLB non-ionic surfactants include, but
are not limited to, nonylphenoxy and octylphenoxy
poly(ethyleneoxy)ethanols (available as the IGEPAL.RTM. CA and CO
series, respectively from Rhodia, Cranbury, N.J.), C.sub.8 to
C.sub.18 ethoxylated primary alcohols (such as RHODASURF.RTM. LA-9
from Rhodia Inc., Cranbury, N.J.), Cl.sub.1 to C.sub.1-5
secondary-alcohol ethoxylates (available as the TERGITOL.TM. 15-S
series, including 15-S-7, 15-S-9, 15-S-12, from Dow Chemical
Company, Midland, Mich.), polyoxyethylene sorbitan fatty acid
esters (available as the TWEEN.RTM. series of surfactants from
Uniquema, Wilmington, Del.), polyethylene oxide (25) oleyl ether
(available as SIPONIC.TM. Y-500-70 from American Alcolac Chemical
Co., Baltimore, Md.), alkylaryl polyether alcohols (available as
the TRITON.TM. X series, including X-100, X-165, X-305, and X-405,
from Dow Chemical Company, Midland, Mich.).
[0023] The initiation system utilized in the first reaction mixture
can be any suitable system for generating free radicals necessary
to facilitate emulsion polymerization. The initiator can be added
in an amount such that the molar ratio of monomer(s) to initiator
in the first reaction mixture is in the range of from about 1,000:1
to about 5,000,000:1, about 2,500:1 to about 2,500,000:1, or
5,000:1 to 2,000,000:1. Examples of possible initiators include,
but are not limited to, persulfates (e.g., ammonium persulfate,
sodium persulfate, potassium persulfate), peroxy persulfates, and
peroxides (e.g., tert-butyl hydroperoxide).
[0024] Optionally, the initiation system can comprise one or more
reducing components and/or one or more accelerators. In one
embodiment, the first reaction mixture can have a molar ratio of
monomer(s) to reducing component in the range of from about 1,000:1
to about 5,000,000:1, about 2,500:1 to about 2,500,000:1, or
5,000:1 to 2,000.000:1. Examples of reducing components can
include, but are not limited to, bisulfites, metabisulfites,
ascorbic acid, erythorbic acid, and sodium formaldehyde
sulfoxylate. In another embodiment, an accelerator can be added to
achieve an accelerator to initiator molar ratio in the range of
from about 0.001:1 to about 10:1, about 0.0025:1 to about 5:1, or
0.005:1 to 1:1. Examples of accelerators can include, but are not
limited to, compositions containing a transition metal having two
oxidation states such as, for example, ferrous sulfate and ferrous
ammonium sulfate. Alternatively, thermal and radiation initiation
techniques can be employed to generate the free radicals. If a
polymerization technique other than emulsion polymerization is
utilized, the initiation and/or catalytic methods corresponding to
the selected polymerization technique may also be employed. For
example, addition or condensation polymerization is performed, the
polymerization can be initiated or catalyzed by cationic, anionic,
or coordination type methods.
[0025] Optionally, the first reaction mixture can include at least
one hydrate inhibitor. The hydrate inhibitor can comprise a
thermodynamic hydrate inhibitor. Alcohols and polyols are two
examples of hydrate inhibitors. In one embodiment, the hydrate
inhibitor can comprise one or more polyhydric alcohols and/or one
or more ethers of polyhydric alcohols. Examples of suitable hydrate
inhibitors can include but are not limited to, monoethylene glycol,
diethylene glycol, triethylene glycol, monopropylene glycol,
dipropylene glycol, ethylene glycol monomethyl ether, diethylene
glycol monomethyl ether, propylene glycol monomethyl ether,
dipropylene clycol monomethyl ether, and mixtures thereof. If a
hydrate inhibitor is employed, the first reaction mixture can have
a hydrate inhibitor-to-water weight ratio in the range of from
about 1:10 to about 10:1, about 1:5 to about 5:1, or 2:3 to
3:2.
[0026] According to one embodiment of the present invention, the
monomer(s), liquid continuous phase, emulsion stabilizer(s), and
hydrate inhibitor (if present) can be combined under a
substantially oxygen-free atmosphere comprising less than about
1,000 parts per million by weight (ppmw), less than about 500 ppmw,
or less than 100 ppmw of oxygen prior to initiating polymerization.
The oxygen-free atmosphere can be maintained by continuously
purging the reaction vessel with an inert gas such as nitrogen
and/or argon. Generally, the reactor system can be operated at a
temperature ranging from about the freezing point of the reaction
mixture to about 60.degree. C., about 0 to about 45.degree. C., or
1 to 30.degree. C. and a pressure in the range of from about 5 to
about 100 pounds per square inch, absolute (psia), about 10 to
about 25 psia, or at about atmospheric pressure. However, pressures
up to and exceeding about 300 psia may be required to polymerize
certain monomers, such as, for example, diolefins.
[0027] In order to initiate polymerization, the pH of the first
reaction mixture can be in the range of from about 5 to about 11,
about 6 to about 10.5, or 6.5 to 10, If necessary, a buffer
solution can be added to the first reaction mixture prior to the
introduction of the initiation system to achieve and/or maintain
the desired reaction pH. Typically, the type of buffer added to the
first reaction mixture can be selected according to its
compatibility with the chosen initiation system. Examples of
buffers can include, but are not limited to, carbonate, phosphate,
and/or borate buffers.
[0028] To initiate polymerization, the initiation system described
above can be added to the reactor via a single injection or over a
time period of at least about 15 minutes, or in the range of from
about 20 minutes to about 5 hours or 30 minutes to 2.5 hours. As
the reaction is carried out, the reactor contents can be
continuously stirred and the polymerization can continue for a
period of time sufficient to convert at least about 90 weight
percent of the monomers in the reaction mixture. Typically, the
first polymerization step can be carried out for a period of time
in the range of from about 1 to about 10 hours, about 2 to about 8
hours, or 3 to 5 hours.
[0029] The first emulsion polymerization step yields a latex
composition comprising a plurality of solid particles dispersed in
a liquid continuous phase. In general, the latex can comprise the
solid particles in an amount in the range of from about 10 to about
60 weight percent, about 15 to about 55, or 20 to 50 weight
percent. The liquid continuous phase of the latex composition can
comprise water, emulsion stabilizers), hydrate inhibitor (if
present), and/or buffer (if present). Typically, the latex can
comprise water in an amount in the range of from about 10 to about
80, about 35 to about 75, or 40 to 60 weight percent, and the
emulsion stabilizer in an amount in the range of from about 0.1 to
about 10, about 0.25 to about 8, or 0.5 to 6 weight percent.
[0030] In one embodiment of the present invention, the latex
particles of the latex composition resulting from the first
emulsion polymerization step can be subsequently used as core
particles of a yet-to-be-described second latex composition
comprising core-shell particles (i.e., a core-shell latex
composition). In one embodiment, the core particles can comprise a
drag reducing polymer. In another embodiment, the core particles
can comprise a non-polyalphaolefin drag reducing polymer.
Additionally, the core particles can comprise repeating units of
the residues of C.sub.4-C.sub.2 alkyl, C.sub.6-C.sub.20 substituted
or unsubstituted aryl, or aryl-substituted C.sub.1-C.sub.10 alkyl
ester derivatives of methacrylic or acrylic acid. In another
embodiment, the core particles can comprise a copolymer having
repeating units of the residues of 2-ethylhexyl methacrylate and
the residues of at least one other monomer. In yet another
embodiment, the core particles can comprise a copolymer having
repeating units of the residues of 2-ethylhexyl methacrylate
monomers and butyl acrylate monomers. In still another embodiment,
the core particles can comprise a homopolymer having repeating
units of residues of 2-ethylhexyl methacrylate (EHMA).
[0031] In one embodiment of the present invention, the core
particles can be formed of a drag reducing polymer having a weight
average molecular weight (M.sub.w) of at least about
5.times.10.sup.6 g/mol, at least about 1.times.10.sup.7 g/mol, or
at least 2.times.10.sup.7 g/mol. The core particles can have a mean
particle size of less than about 10 microns, less than about 1.000
nm (1 micron), in the range of from about 10 to about 500 nm, or in
the range of from 50 to 250 mm. In one embodiment, at least about
95 weight percent of the core particles can have a particle size in
the range of from about 10 nm to about 500 nm and at least about 95
weight percent of the particles can have a particle size in the
range of from about 25 nm to about 250 nm.
[0032] In accordance with one embodiment of the present invention,
at least a portion or substantially all of the first latex
composition can be exposed to a second polymerization step to
thereby produce a core-shell latex composition. According to one
embodiment of the present invention, the second polymerization step
comprises emulsion polymerization and does not include interfacial
polymerization, suspension polymerization, and/or rotating disk
polymerization or complex coacervation processes. Typically, the
second emulsion polymerization step can be carried out by
copolymerizing one or more hydrophobic monomers and one or more
amphiphilic compounds in the presence of an initiation system to
thereby form a shell copolymer. The shell copolymer can form shells
that at least partly surround or entirely surround at least a
portion of the individual core latex particles formed in the first
polymerization step to thereby produce a plurality of core-shell
latex particles.
[0033] In general, the hydrophobic monomer(s) utilized in the
second emulsion polymerization step can include hydrophobic
monomers having a weight average molecular weight in the range of
from about 50 to about 400, about 100 to about 350, or 150 to 310
grams per mole (g/mole). One or more of the monomers (A)-(Q)
previously discussed with reference to the first emulsion
polymerization step can be employed as the hydrophobic monomer to
form the shell copolymer in the second emulsion polymerization
step. In one embodiment, the hydrophobic monomer is an acrylate
and/or methacrylate monomer, such as, for example, 2-ethylhexyl
methacrylate.
[0034] Generally, the amphiphilic compound(s) utilized in the
second emulsion polymerization step can have a weight average
molecular weight of at least about 100 g/mole or in the range of
from about 200 to about 5,000, or 300 to 2,500 g/mole. In one
embodiment, the amphiphilic compounds can comprise one or more
surfactants having an HLB number in the range of from about 6 to
about 19, about 9 to about 17, or 11 to 16. In addition, the one or
more surfactants utilized in the second polymerization step can
comprise an ionic and/or a non-ionic polymerizable surfactant. In
one embodiment, the second emulsion polymerization step can be
carried out in the presence of at least one ionic polymerizable
surfactant and at least one non-ionic polymerizable surfactant.
Examples of suitable surfactants can include, but are not limited
to polyethylene glycol methacrylate (available as the Blemmer.RTM.
PE and PEG series of surfactants from Nippon Oil & Fats Co.
Ltd. Tokyo, Japan), propylene glycol methacrylate (available as the
Blemmer.RTM. PP series of surfactants from Nippon Oil & Fats
Co., Ltd., Tokyo, Japan), styrene sulfonic acid sodium salt,
2-acrylamidoglycolic acid (available from Sigma-Aldrich Corp., St.
Louis, Mo.), (acrylamidomethul)cellulose acetate propionate,
ionized or non-ionized 2-acrylamido-2-methyl-1-propanesulfonic acid
(available as the AMPS.RTM. monomer series from Lubrizol Advanced
Materials Inc., Wickliffe, Ohio), 3-sulfopropyl acrylate potassium
salt (available from Taiwan Hopax Chemical Manufacturing Co.,
Kaohsiung, Taiwan), 3-sulfopropyl methacrylate potassium salt,
ionized or non-ionized methacrylic acid, and ionized or non-ionized
acrylic acid (each available from Sigma-Aldrich Corp., St. Louis.
Mo.).
[0035] The initiation system utilized in the second emulsion
polymerization step can comprise any of the previously-discussed
initiators, including, for example, persulfates (e.g., ammonium
persulfate, sodium persulfate, potassium persulfate), peroxy
persulfates, and peroxides (e.g., tert-butyl hydroperoxide).
Optionally, the reaction mixture of the second polymerization step
can also include one or more accelerators and/or reducing
components according to the ratios discussed above.
[0036] As discussed previously, in one embodiment, the second
polymerization step can be initiated by first charging a reactor
with at least a portion or substantially all of the first latex
composition isolated from the reactor of the first polymerization
step and stored for a period of time before performing the second
polymerization step. Alternatively, at least a portion or
substantially all of the first latex composition can remain in the
reactor and the second polymerization step can be carried out
immediately after the first polymerization step in the same
reaction vessel.
[0037] According to one embodiment of the present invention, the
latex composition charged to the reactor can be agitated and purged
with an inert gas (e.g., nitrogen) to create a substantially
oxygen-free environment. The latex composition can then be heated
to a temperature greater than about 50.degree. C., or in the range
of from about 60 to about 110.degree. C., or 75 to 95.degree. C.
prior to adding the initiation system, monomer(s), and amphiphilic
compound(s). In one embodiment, the second emulsion polymerization
step can be carried out in a semi-continuous manner tinder
monomer-starved conditions by adding the total volume of one or
more of the above-described reactant(s) over a time period of at
least about 10 minutes, at least about 15 minutes, at least about
30 minutes, at least about 1 hour, or at least 2 hours.
[0038] Typically, the second reaction mixture can be continuously
agitated during polymerization so that the reaction takes place
under high shear conditions. In general, the second polymerization
step can be continued long enough that at least about 80, at least
about 90, or at least 95 weight percent of the monomer(s) have been
polymerized.
[0039] In one embodiment, the resulting shell copolymer can
comprise repeat units of the monomer(s) in an amount in the range
of from about 25 to about 98, about 50 to about 95, or 70 to 90
weight percent, based on the total weight of the resulting shell
copolymer. In one embodiment wherein non-ionic and ionic
polymerizable surfactants are used, the resulting shell copolymer
can comprise repeat units of the non-ionic polymerizable surfactant
in an amount in the range of from about 2 to about 50, about 4 to
about 40, or 8 to 25 weight percent and can comprise repeat units
of the ionic polymerizable surfactant in an amount in the range of
from about 0.05 to about 30, about 1 to about 20, or 2 to 15 weight
percent, based on the total weight of the shell copolymer. The
weight ratio of repeat units of the monomer(s) to repeat units of
the non-ionic polymerizable surfactant in the shell copolymer can
be in the range of from about 0.5:1 to about 40:1, about 1:1 to
about 20:1, or 2:1 to 10:1 and the weight ratio of the monomer
repeat units to the repeat units of the ionic polymerizable
surfactant can be in the range of from about 1:1 to about 100:1,
about 3:1 to about 50:1, or 5:1 to 30:1. In one embodiment, the
weight ratio of the repeat units of the non-ionic polymerizable
surfactant to the repeat units of the ionic polymerizable
surfactant in the shell copolymer can be in the range of from about
0.25:1 to about 30:1, about 0.75:1 to about 10:1, or 1.5:1 to
6:1.
[0040] The second emulsion polymerization step can yield a latex
composition comprising a plurality of solid core-shell particles
dispersed a liquid continuous phase. In general, the latex can
comprise the particles in an amount in the range of from about 10
to about 60 weight percent, about 15 to about 55, or 20 to 50
weight percent. The liquid continuous phase of the latex
composition can comprise water, emulsion stabilizer(s), and hydrate
inhibitor (if present), and/or buffer (if present). Typically, the
latex can comprise water in an amount in the range of from about 10
to about 80, about 35 to about 75, or 40 to 60 weight percent, and
the emulsion stabilizer(s) in an amount in the range of from about
0.1 to about 10, about 0.25 to about 8, or 0.5 to 6 weight percent.
In one embodiment, the liquid continuous phase can comprise a
mixture of water and ethylene glycol and/or propylene glycol.
Generally, the latex composition can have a viscosity of less than
about 1,000 centipoise (cp), or in the range of from about 1 to
about 100 or 2 to 700 cp, measured at a shear rate of 511
sec.sup.-1 and a temperature of 75.degree. F.
[0041] According to one embodiment, at least a portion of the
shells of the dispersed particles of the latex composition produced
during the second emulsion polymerization step can at least partly
or entirely surround at least a portion of the core particles
without being chemically or physically bound to the cores. In one
embodiment, the shell copolymer can be a non-drag-reducing
copolymer.
[0042] Typically, the core-shell particles can have a mean particle
size of less than about 10 microns, less than about 1,000 nm (1
micron), in the range of from about 10 to about 750 nm, or in the
range of from 50 to 250 nm. In one embodiment, at least about 90
weight percent of the core-shell particles have a particle size
greater than 25 nanometers and/or less than 500 nanometers.
According to one embodiment, the core-shell particles can have an
average weight ratio of the core to the shell in the range of from
about 1.5:1 to about 30:1, about 2:1 to about 20:1, or 4:1 to 15:1.
In general the shell constitutes in the range of from about 2 to
about 40, about 5 to about 30, or 10 to 25 weight percent of the
total weight of the core-shell particle and can have an average
thickness in the range of from about 0.1 to about 20, about 0.5 to
about 15, or 1 to 10 percent of the mean particle diameter of the
total core-shell particle. Typically, the average shell thickness
can be in the range of from about 0.5 to about 30, about 1 to about
20, or 2 to 15 nm.
[0043] In one embodiment of the present invention, the
above-described core-shell flow improving composition can be added
to a hydrocarbon-containing fluid flowing through a fluid conduit.
In one embodiment, the hydrocarbon-containing fluid can comprise
crude oil, gasoline, diesel, and/or other refined products. The
flow improver can be added to the fluid conduit via one or more
injection pumps at one or more locations along the length of the
conduit. In one embodiment, the injection pump can have a discharge
pressure greater than about 500 psig, or in the range of from about
600 to about 2,500 psig, or 750 to 1,500 psig.
[0044] Typically, the amount of flow improver added to the treated
hydrocarbon-containing fluid is such that the fluid can experience
a drag reduction of at least about 5 percent, at least about 10
percent, or at least 15 percent compared to the untreated fluid. In
one embodiment, the cumulative concentration of the drag reducing
core polymer in the treated fluid can be in the range of from about
0.1 to about 500 ppmw, about 0.5 to about 200 ppmw, about 1 to
about 100 ppmw, or 2 to 50 ppmw. Typically, at least about 50
weight percent, at least about 75 weight percent, or at least 95
weight percent of the core-shell particles of the flow-improving
composition can be dissolved by the hydrocarbon-containing
fluid.
[0045] The following examples are intended to be illustrative of
the present invention in order to teach one of ordinary skill in
the art to make and use the invention and are not intended to limit
the scope of the invention in any way.
EXAMPLES
Test Method
[0046] In the Examples that follow, the test method described below
was used for determining the pumping stability of latex flow
improving compositions. FIG. 1 depicts a test apparatus 10 used for
the pumping stability tests.
[0047] The pumping stability test were initiated by gravity feeding
a latex flow improver from a 165-gallon feed tank 12 into the
suction of a Milton Roy C High Performance Diaphragm (HPD) Metering
pump 14 (available from Milton Roy USA in Ivyland, Pa.). The flow
improver was filtered with a 100-micron filter 16 and then pumped
at a rate corresponding to 50 percent stroke length through 3000
feet of 1/2 inch diameter (0.049 inch wall thickness) stainless
steel coiled tubing 18 prior to reentering feed tank 12 via return
line 20, as shown in FIG. 1. To minimize product foaming, the
outlet of return line 20 was positioned below the liquid level in
feed tank 12. The mass flow rate of the circulating flow improver
was monitored via an Endress+Hauser coriolis flow meter 22
(available from Endress+Hauser, Inc. in Greenwood, Ind.) and
graphically recorded over the duration of the experiment. The flow
improver was allowed to circulate continuously through test
apparatus 10 for a period of 6 weeks or until pump failure
occurred. Upon conclusion of the test, apparatus 10 was dismantled
and pump 14, filter 16, and coiled tubing 18 were visually
inspected and the observations were documented.
Example 1
Synthesis of a Comparative Latex Flow Improver
[0048] Latex Flow Improver A (comparative) was prepared by emulsion
polymerization according to the following procedure.
[0049] Polymerization was performed in a 185-gallon stainless
steel, jacketed reactor with a mechanical stirrer, thermocouple,
feed ports, and nitrogen inlets/outlets. The reactor was charged
with 440 lbs of monomer (2-ethylhexyl methacrylate), 288.9 lbs of
de-ionized water, 279.0 lbs of monoethylene glycol, 41.4 lbs of
Polystep.RTM. B-5 (surfactant, available from Stepan Company of
Northfield, Ill.), 44 lbs of Tergitol.TM. 15-S-7 (surfactant,
available from Dow Chemical Company of Midland, Mich.), 1.24 lbs of
potassium phosphate monobasic (pH buffer), 0.97 lbs of potassium
phosphate dibasic (pH buffer), and 33.2 grams of ammonium
persulfate, NH.sub.4).sub.2S.sub.2O.sub.8 (oxidizer).
[0050] The monomer, water, and monoethylene glycol mixture was
agitated at 110 rpm while being cooled to 41.degree. F. The two
surfactants were added and the agitation was slowed down to 80 rpm
for the remainder of the reaction. The buffers and the oxidizer
were then added. The polymerization reaction was initiated by
adding 4.02 grams of ammonium iron(II)sulfate,
Fe(NH.sub.4).sub.2(SO.sub.4).sub.2.6H.sub.2O in a solution of 0.010
M sulfuric acid solution in de-ionized water at a concentration of
1117 ppm at a rate of 5 g/min into the reactor. The solution was
injected for 10 hours to complete the polymerization. The resulting
latex was pressured out of the reactor through a 5-micron bag
filter and stored.
Example 2
Synthesis of an Inventive Latex Flow Improver
[0051] Latex Flow Improver B (inventive) was prepared by emulsion
polymerization according to the following procedure.
[0052] One thousand pounds of Latex Flow Improver A, as prepared
according to the procedure of Example 1, was charged into a
stainless steel jacketed reactor having a mechanical stirrer,
thermocouple, feed ports, and nitrogen inlets and outlets. The flow
improver was agitated at a speed of 80 rpm under a constant
nitrogen purge while being heated to 176.degree. F. Next, 4011
grams of an aqueous solution comprising 25.21 weight percent
ammonium persulfate, (NH.sub.4).sub.2S.sub.2O.sub.8 (an oxidizer)
was injected into the reactor and the reactor contents were allowed
to stir for 30 minutes. Next, the following three reactants were
simultaneously injected into the reactor: (1) an aqueous solution
comprising 25.85 weight percent ammonium persulfate; (2) an aqueous
solution comprising methoxypolyethylene glycol 500 methacrylate,
13.33 weight percent sodium styrene sulfonate, and 46.67 weight
percent de-ionized water; and (3) 2-ethylhexyl methacrylate.
Reactant (1) was injected into the reactor at a rate of 20 grams
per minute (g/min) for 2.5 hours, reactant (2) was injected at a
rage of 113.4 g/min for 2 hours, and reactant stream (3) was
injected into the reactor at 215.0 g/min for 2.25 hours. After the
injection of reactant (1) was completed, the reactor contents were
then held for 30 minutes at 176.degree. F. while agitating at 80
rpm. The resulting latex was then cooled to below 100.degree. F.,
pressured out of the reactor through a 5-micron bag filter and
stored.
Example 3
Pumping Stability Tests
[0053] Latex Flow Improver A (comparative) and Latex Flow Improver
B (inventive) were subjected to the above-described test method to
determine the relative pumping stability of each composition. The
results of these experiments are illustrated in FIGS. 2 and 3.
[0054] FIG. 2 is a plot of the mass flow rate of Latex Flow
Improver A versus time. After less than 4 days, the trial was
stopped due to extended periods of erratic, low, or no fluid flow,
as shown in FIG. 2. The pump was disassembled and showed
considerable build up of a polymeric film. In addition, large
pieces of polymeric material were found in downstream valves and
piping.
[0055] FIG. 3 is a plot of the mass flow rate of Latex Flow
Improver B versus time. As shown in FIG. 3. Latex Flow Improver B
circulated for a period of 41 days without substantial flow
interruption. The test was stopped after 41 days and the equipment
(pump and downstream filter, valves, and piping) were disassembled.
Upon inspection, the pump showed very little film build-up and no
material was found in the pump check valves downstream of the pump
discharge.
[0056] Thus, as Latex Flow Improver B flowed longer without
interruption and showed little evidence of film build up, Latex
Flow Improver B demonstrates a higher pumping stability than Latex
Flow Improver A.
Numerical Ranges
[0057] The present description uses numerical ranges to quantify
certain parameters relating to the invention. It should be
understood that when numerical ranges are provided, such ranges are
to be construed as providing literal support for claim limitations
that only recite the lower value of the range as well as claims
limitation that only recite the upper value of the range. For
example, a disclosed numerical range of 10 to 100 provides literal
support for a claim reciting "greater than 10" (with no upper
bounds) and a claim reciting "less than 100" (with no lower
bounds).
DEFINITIONS
[0058] As used herein, the terms "a," "an," "the," and "said" mean
one or more.
[0059] As used herein, the term "amphiphilic" refers to a compound
having both hydrophobic and hydrophobic moieties.
[0060] As used herein, the term "and/or," when used in a list of
two or more items, means that any one of the listed items can be
employed by itself or any combination of two or more of the listed
items can be employed. For example, if a composition is described
as containing components A, B, and/or C, the composition can
contain A alone; B alone; C alone; A and B in combination; A and C
in combination; B and C in combination; or A, B, and C in
combination.
[0061] As used herein, the terms "comprising," "comprises," and
"comprise" are open-ended transition terms used to transition from
a subject recited before the term to one or more elements recited
after the term, where the element or elements listed after the
transition term are not necessarily the only elements that make up
the subject.
[0062] As used herein, the terms "containing," "contains," and
"contain" have the same open-ended meaning as "comprising,"
"comprises," and "comprise" provided above.
[0063] As used herein, the terms "including," "includes," and
"include" have the same open-ended meaning as "comprising,"
"comprises," and "comprise" provided above.
[0064] As used herein, the terms "having," "has," and "have" have
the same open-ended meaning as "comprising," "comprises," and
"comprise" provided above.
[0065] As used herein, the term "drag reducing polymer" refers to a
polymer having a weight average molecular weight of at least
5.times.10.sup.6 g/mol that, when added to a fluid flowing through
a conduit, is effective to reduce pressure loss associated with
turbulent flow of the fluid through the conduit.
[0066] As used herein, the term "HLB number" refers to the
hydrophile-lipophile balance of an amphiphilic compound as
determined by the methods described by W. C. Griffin in J. Soc.
Cosmet. Chem., 1, 311 (1949) and J. Soc. Cosmet. Chem., 5, 249
(1954).
[0067] As used herein, the term "polymer" refers to homopolymers,
copolymers, terpolymers of one or more chemical species.
[0068] As used herein, the term "polymerizable surfactant" refers
to a surfactant having at least one ethylenically unsaturated
moiety.
[0069] As used herein, the term "turbulent flow" refers to fluid
flow having a Reynolds number of at least 2,000.
[0070] As used herein, the term "weight average molecular weight"
refers to the molecular weight of a polymer calculated according to
the following formula:
.SIGMA..sub.i(N.sub.iM.sub.i.sup.2)/.SIGMA..sub.i(N.sub.iM.sub.i),
where N.sub.i is the number of molecules of molecular weight
M.sub.i.
Claims not Limited to the Disclosed Embodiments
[0071] The preferred forms of the invention described above are to
be used as illustration only, and should not be used in a limiting
sense to interpret the scope of the present invention.
Modifications to the exemplary embodiments, set forth above, could
be readily made by those skilled in the art without departing from
the spirit of the present invention.
[0072] The inventors hereby state their intent to rely on the
Doctrine of Equivalents to determine and assess the reasonably fair
scope of the present invention as pertains to any apparatus not
materially departing from but outside the literal scope of the
invention as set forth in the following claims.
* * * * *