U.S. patent application number 14/108469 was filed with the patent office on 2014-06-19 for polymer formulations in solvents with a high flashpoint, processes for production thereof and use thereof as pour point depressants for crude oils, mineral oils or mineral oil products.
This patent application is currently assigned to BASF SE. The applicant listed for this patent is BASF SE. Invention is credited to Dieter Faul, Stefen Frenzel, Ivette Garcia Castro, Kai Gumlich, Maria Heuken, Rouven Konrad, Karin Neubecker.
Application Number | 20140166287 14/108469 |
Document ID | / |
Family ID | 50929607 |
Filed Date | 2014-06-19 |
United States Patent
Application |
20140166287 |
Kind Code |
A1 |
Faul; Dieter ; et
al. |
June 19, 2014 |
POLYMER FORMULATIONS IN SOLVENTS WITH A HIGH FLASHPOINT, PROCESSES
FOR PRODUCTION THEREOF AND USE THEREOF AS POUR POINT DEPRESSANTS
FOR CRUDE OILS, MINERAL OILS OR MINERAL OIL PRODUCTS
Abstract
Polymer formulations comprising at least two different solvents
having a flashpoint .gtoreq.60.degree. C., and polymeric
compositions obtainable by free-radical polymerization of at least
one alkyl (meth)acrylate in the presence of at least one
ethylene-vinyl ester copolymer. Multistage process for producing
such formulations and the use of such formulations as pour point
depressants for crude oils, mineral oils or mineral oil
products.
Inventors: |
Faul; Dieter;
(Niederkirchen, DE) ; Garcia Castro; Ivette;
(Ludwigshafen, DE) ; Gumlich; Kai; (Koln, DE)
; Heuken; Maria; (Mannheim, DE) ; Konrad;
Rouven; (Morstadt, DE) ; Neubecker; Karin;
(Frankenthal, DE) ; Frenzel; Stefen; (Eislingen,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BASF SE |
Ludwigshafen |
|
DE |
|
|
Assignee: |
BASF SE
Ludwigshafen
DE
|
Family ID: |
50929607 |
Appl. No.: |
14/108469 |
Filed: |
December 17, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61738417 |
Dec 18, 2012 |
|
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|
Current U.S.
Class: |
166/305.1 ;
44/393 |
Current CPC
Class: |
E21B 43/16 20130101;
C10M 2203/1006 20130101; C10M 2209/062 20130101; C10N 2020/04
20130101; C10M 177/00 20130101; C10M 145/14 20130101; C10M 2205/022
20130101; C10M 2209/084 20130101; C10M 159/005 20130101; C10N
2030/02 20130101; C10M 2205/022 20130101; C10M 2209/062 20130101;
C10M 2209/084 20130101 |
Class at
Publication: |
166/305.1 ;
44/393 |
International
Class: |
C10L 10/16 20060101
C10L010/16; E21B 43/16 20060101 E21B043/16 |
Claims
1. A process for producing a polymer formulation at least
comprising two different solvents and a polymeric composition
obtainable by free-radical polymerization of at least one
monoethylenically unsaturated monomer (A) in the presence of at
least one ethylene-vinyl ester copolymer (B), the monomers (A)
comprising at least 70% by weight - based on the amount of all
monomers (A)--of at least one alkyl (meth)acrylate (A1) of the
general formula H.sub.2C=CR.sup.1-COOR.sup.2where R.sup.1 is H or a
methyl group and R.sup.2 is a linear alkyl radical having 12 to 60
carbon atoms, the ethylene-vinyl ester copolymers (B) comprising 55
to 85% by weight of ethylene and 15 to 45% by weight of vinyl
esters of the general formula H.sub.2C=CH-O-(O)C-R.sup.3 (III)
where R.sup.3 is H or a C.sub.1- to C.sub.4 hydrocarbyl radical,
and the amount of the monomers (A) being 70 to 90% by weight and
that of the ethylene-vinyl ester copolymers (B) 10 to 30% by weight
based on the sum of the monomers (A) and the ethylene-vinyl ester
copolymers (B) together, wherein the solvents comprise a nonpolar
solvent (S1) comprising saturated aliphatic hydrocarbyl groups and
having a flashpoint .gtoreq.60.degree. C., and an aromatic
hydrocarbon (S2) having a flashpoint >60.degree. C., said
process comprising: (I) providing a solution at least comprising
monomers (A) and ethylene-vinyl ester copolymers (B) each in the
abovementioned amounts in at least one solvent (S1), and (II)
free-radically polymerizing the monomers (A) in the presence of the
ethylene-vinyl ester copolymers (B) by addition of at least one
thermally decomposing initiator for the free-radical polymerization
to the solution obtained in (I) and polymerizing at a temperature
of at least 50.degree. C., the reaction medium being diluted with
solvent (S2) during and/or after the polymerization.
2. The process according to claim 1, wherein solvent (S1) comprises
saturated aliphatic hydrocarbons having a flashpoint
.gtoreq.60.degree. C.
3. The process according to claim 2, wherein process step (I)
comprises the following component steps: (Ia) preparation of a
solution comprising alkyl (meth)acrylates (A1) in at least one
aliphatic hydrocarbon as solvent (S1) by esterifying at least one
alcohol of the general formula R.sup.2-OH with (meth)acrylic acid
H.sub.2C=CR.sup.1-COOH in the presence of solvents (S1), and (Ib)
mixing the solution obtained in process step (Ia) with at least one
ethylene-vinyl ester copolymer (B) and optionally further monomers
(A) other than (A1).
4. The process according to claim 1, wherein a portion of the
solvents solvent (S2) is added during the polymerization and a
portion of the solvents solvent (S2) is added after the
polymerization.
5. The process according to claim 1, wherein the weight ratio of
the solvents S1/S2 is 1:5 to 2:1.
6. The process according to claim 1, wherein the concentration of
the monomers (A) in the solvent (S1) at the start of process step
(II) is 50 to 85% by weight.
7. The process according to claim 1, wherein the amount of the
solvents (S1) and (S2) is such that the concentration of all
polymers prepared together at the end of process step (II) is 35 to
55% by weight based on the sum of all components of the
solution.
8. The process according to claim 1, wherein the amount of the
solvents (S1) and (S2) is such that the concentration of all
polymers prepared together at the end of process step (II) is 40 to
50% by weight based on the sum of all components of the
solution.
9. The process according to claim 1, wherein the mean molecular
weight M.sub.w of the ethylene-vinyl ester copolymers (B) used is
at least 30 000 g/mol.
10. The process according to claim 1, wherein the ethylene-vinyl
ester copolymers (B) comprise 55 to 75% by weight of ethylene and
25 to 45% by weight of vinyl esters.
11. The process according to claim 1, wherein the ethylene-vinyl
ester copolymers (B) comprise 60 to 70% by weight of ethylene and
30 to 40% by weight of vinyl esters.
12. The process according to claim 1, wherein R.sup.3 is a methyl
radical.
13. The process according to claim 1, wherein R.sup.2 is a linear
alkyl radical having 16 to 30 carbon atoms.
14. The process according to claim 1, wherein R.sup.2 is a linear
alkyl radical having 18 to 24 carbon atoms.
15. The process according to claim 1, wherein the amount of the
monomers (A) is 75 to 85% by weight and that of the ethylene-vinyl
ester copolymers (B) 15 to 25% by weight based on the sum of
monomers (A) and ethylene- vinyl ester copolymers (B).
16. The process according to claim 1, wherein the monomers (A)
used, as well as monomers (Al), are different (meth)acrylates (A2)
of the general formula H.sub.2C=CR.sup.1-COOR.sup.4where R.sup.1 is
H or methyl and R.sup.4 is a hydrocarbyl radical selected from the
group of R.sup.4a, R.sup.4b, R.sup.4c and R.sup.4d radicals and the
radicals are each defined as follows: R.sup.4a: linear alkyl
radicals having 1 to 11 carbon atoms, R.sup.4b: branched alkyl
radicals having 4 to 60 carbon atoms, R.sup.4c: unsubstituted or
alkyl-substituted saturated cyclic hydrocarbyl radicals having 5 to
30 carbon atoms, or R.sup.4d:unsubstituted or alkyl-substituted
aromatic hydrocarbyl radicals having 6 to 30 carbon atoms.
17. The process according to claim 1, wherein the monomers (A) used
are exclusively alkyl (meth)acrylates (Al).
18. A polymer formulation comprising two different solvents and a
polymeric composition obtainable by free-radical polymerization of
at least one monoethylenically unsaturated monomer (A) in the
presence of at least one ethylene-vinyl ester copolymer (B), the
monomers (A) comprising at least 70% by weight--based on the amount
of all monomers (A)--of at least one alkyl (meth)acrylate (A1) of
the general formula H.sub.2C=CR.sup.1-COOR.sup.2where R.sup.1 is H
or a methyl group and R.sup.2 is a linear alkyl radical having 12
to 60 carbon atoms, the ethylene-vinyl ester copolymers (B)
comprising 55 to 85% by weight of ethylene and 15 to 45% by weight
of vinyl esters of the general formula H.sub.2C=CH-O-(O)C-R.sup.3
(III) where R.sup.3 is H or a C.sub.1- to C.sub.4 hydrocarbyl
radical, and the amount of the monomers (A) being 70 to 90% by
weight and that of the ethylene-vinyl ester copolymers (B) 10 to
30% by weight based on the sum of the monomers (A) and the
ethylene-vinyl ester copolymers (B) together, wherein the solvents
comprise at least a nonpolar solvent (S1) comprising saturated
aliphatic hydrocarbyl groups and having a flashpoint
.gtoreq.60.degree. C., and an aromatic hydrocarbon (S2) having a
flashpoint 60.degree. C.
19. The formulation according to claim 18, wherein solvent (S1)
comprises saturated aliphatic hydrocarbons having a flashpoint
>60.degree. C.
20. The process according to claim 18 or 19, wherein the weight
ratio S1/S2 is 1:5 to 2:1.
21. The formulation according to claim 18, wherein the
concentration of all polymers together is 35 to 55% by weight based
on the sum of all constituents of the formulation.
22. The formulation according to claim 18, wherein the
concentration of all polymers together is 40 to 50% by weight based
on the sum of all constituents of the formulation.
23. The formulation according to claim 18, wherein the mean
molecular weight M.sub.w of the ethylene-vinyl ester copolymers (B)
used is at least 30 000 g/mol.
24. The formulation according to claim 18, wherein the
ethylene-vinyl ester copolymers (B) comprise 55 to 75% by weight of
ethylene and 25 to 45% by weight of vinyl esters.
25. The formulation according to claim 18, wherein the
ethylene-vinyl ester copolymers (B) comprise 60 to 70% by weight of
ethylene and 30 to 40% by weight of vinyl esters.
26. The formulation according to claim 18, wherein R.sup.3 is a
methyl radical.
27. The formulation according to claim 18, wherein R.sup.2 is a
linear alkyl radical having 16 to 30 carbon atoms.
28. The formulation according to claim 18, wherein R.sup.2 is a
linear alkyl radical having 18 to 24 carbon atoms.
29. The formulation according to claim 18, wherein the amount of
the monomers (A) is 75 to 85% by weight and that of the
ethylene-vinyl ester copolymers (B) is 15 to 25% by weight based on
the sum of monomers (A) and ethylene-vinyl ester copolymers
(B).
30. The formulation according to claim 18, wherein the monomers (A)
used, as well as monomers (A), are alkyl (meth)acrylates (A2) of
the general formula H.sub.2C=CR.sup.1-COOR.sup.4 where R.sup.4 is H
or methyl and R.sup.4 is a hydrocarbyl radical selected from the
group of R.sup.4a, R.sup.4b, R.sup.4c and R.sup.4d radicals and the
radicals are each defined as follows: R.sup.4a: linear alkyl
radicals having 1 to 11 carbon atoms, R.sup.4b: branched alkyl
radicals having 4 to 60 carbon atoms, R.sup.4c: unsubstituted or
alkyl-substituted saturated cyclic hydrocarbyl radicals having 5 to
30 carbon atoms, R.sup.4d:unsubstituted or alkyl-substituted
aromatic hydrocarbyl radicals having 6 to 30 carbon atoms.
31. The formulation according to claim 18, wherein the monomers (A)
used are exclusively alkyl (meth)acrylates (A1).
32. The formulation according to claim 18, which is obtainable by
means of a process comprising I. providing a solution comprising
monomers (A) and ethylene-vinyl ester copolymers (B) each in the
abovementioned amounts in at least one solvent (S1), and II.
free-radically polymerizing the monomers (A) in the presence of the
ethylene-vinyl ester copolymers (B) by addition of at least one
thermally decomposing initiator for the free-radical polymerization
to the solution obtained in (I) and polymerizing at a temperature
of at least 50.degree. C., the reaction medium being diluted with
solvent (S2) during and/or after the polymerization.
33-39. (canceled)
40. A process for producing crude oil, mineral oil, and/or mineral
oil products, said process comprising adding at least one
formulation according to claim 18 as a pour point depressant.
41. The process according to claim 40, wherein the formulation used
additionally comprises at least one wax dispersant.
42. The process according to claim 40, wherein the amount added of
the formulation is 50 to 1500 ppm based on the oil.
43. The process according to claim 40, wherein the oil is crude oil
and the formulation is injected into a crude oil pipeline.
44. The process according to claim 40, wherein the oil is crude oil
and the formulation is injected into a production well.
45. The process according to claim 44, wherein the injection is
effected on an offshore platform.
46. A process for prevention of wax deposits on surfaces in contact
with crude oil, mineral oil, and/or mineral oil products, said
process comprising adding at least one formulation according to
claim 1 to the crude oil, mineral oil, and/or mineral oil products.
Description
[0001] Polymer formulations in solvents with a high flashpoint,
processes for production thereof and use thereof as pour point
depressants for crude oils, mineral oils or mineral oil
products
[0002] The present invention relates to polymer formulations
comprising at least two different solvents having a flashpoint
.gtoreq.60.degree. C., and to polymeric compositions obtainable by
free-radical polymerization of at least one alkyl (meth)acrylate in
the presence of at least one ethylene-vinyl ester copolymer. It
further relates to a multistage process for producing such
formulations and the use of such formulations as pour point
depressants for crude oils, mineral oils or mineral oil
products.
[0003] Underground mineral oil formations typically have relatively
high temperatures. After the production of the crude oil to the
surface, the crude oil produced therefore cools down to a greater
or lesser degree according to the production temperature and the
storage or transport conditions.
[0004] According to their origin, crude oils have different
proportions of waxes, which consist essentially of long-chain
n-paraffins. According to the type of crude oil, the proportion of
such paraffins may typically be 1 to 30% by weight of the crude
oil. When the temperature goes below a particular level in the
course of cooling, the paraffins can crystallize, typically in the
form of platelets. The precipitated paraffins considerably impair
the flowability of the oil. The platelet-shaped n-paraffin crystals
can form a kind of house-of-cards structure which encloses the
crude oil, such that the crude oil ceases to flow, even though the
predominant portion is still liquid. The lowest temperature at
which a sample of an oil still just flows in the course of cooling
is referred to as the pour point ("yield point"). For the
measurement of the pour point, standardized test methods are used.
Precipitated paraffins can block filters, pumps, pipelines and
other installations or be deposited in tanks, thus entailing a high
level of cleaning.
[0005] The deposit temperature of oil deposits is generally above
room temperature, for example 40.degree. C. to 100.degree. C. Crude
oil is produced from such deposits while still warm, and it
naturally cools more or less quickly to room temperature in the
course of or after production, or else to lower temperatures under
corresponding climatic conditions. Crude oils may have pour points
above room temperature, so such that crude oils of this kind may
solidify in the course of or after production.
[0006] It is known that the pour point of crude oils can be lowered
by suitable additives. This can prevent paraffins from
precipitating in the course of cooling of produced crude oil.
Suitable additives firstly prevent the formation of said
house-of-cards-like structures and thus lower the temperature at
which the crude oil solidifies. In addition, additives can promote
the formation of fine, well-crystallized, non-agglomerating
paraffin crystals, such that undisrupted oil transport is ensured.
Such additives are referred to as pour point depressants or flow
improvers.
[0007] Paraffin inhibitors or wax inhibitors refer to those
substances intended to prevent the deposition of paraffins or
paraffin waxes on surfaces in contact with crude oils or other
wax-containing oils and/or mineral oil products.
[0008] The use of ethylene copolymers as flow improvers is known,
especially that of copolymers of ethylene and unsaturated esters.
Examples thereof are described in DE-A-21 02 469 or EP 84 148
A2.
[0009] DE-A-16 45 785 discloses heating oil mixtures with a
depressed pour point. The mixtures comprise at least 3% by weight
of polymers having unbranched saturated side chains having at least
18 carbon atoms, for example homo- or copolymers of alkyl esters of
unsaturated mono- and dicarboxylic acids and homo- or copolymers of
various alkyl vinyl ethers.
[0010] DE-A-20 47 448 discloses additives for lowering viscosity in
paraffin-based crude oils. The additives are mixtures of polyvinyl
ethers and ethylene-vinyl acetate copolymers.
[0011] EP 486 836 A1 discloses mineral oil middle distillates, for
example gas oils, diesel oils or heating oil, which comprise
polymeric additives to improve the flow properties under cold
conditions. The polymeric additives are a combination of customary
ethylene-based flow improvers, for example copolymers of ethylene
and vinyl acetate, vinyl propionate or ethylhexyl acrylate and
copolymers of C.sub.8- to C.sub.18-alkyl (meth)acrylates and/or
C.sub.18- to C.sub.28-alkyl vinyl ethers in a weight ratio of 40:60
to 95:5, and the copolymers of the alkyl (meth)acrylates and/or
alkyl vinyl ethers and the conventional flow improvers may be in
the form of a mixture or the copolymers of the alkyl
(meth)acrylates and/or alkyl vinyl ethers may wholly or partly be
grafted onto the conventional flow improvers. The solvents proposed
for performance of the polymerization are a multitude of very
different solvents, for example toluene, xylene, ethyl benzene,
cumene, high-boiling aromatic mixtures, aliphatic and
cycloaliphatic hydrocarbons such as n-hexane, cyclohexane,
methylcyclohexane, n-octane, i-octane, paraffin oils, paraffinic
solvent mixtures or tetrahydrofuran and dioxane. In the sole
example for preparation of a graft copolymer, n-dodecyl acrylate
and n-octadecyl vinyl ether are grafted onto a copolymer of
ethylene and vinyl propionate having a mean molar mass M.sub.n of
approx. 2500 g/mol. The grafting is performed in isoundecane as a
solvent. After the end of the reaction, a high-boiling aromatic
solvent mixture and further ungrafted ethylene-vinyl propionate
copolymer are added.
[0012] U.S. Pat. No. 4,608,411 discloses graft copolymers for
prevention of wax deposition from crude oils. The main chain
consists of a copolymer of ethylene and a monomer selected from the
group of vinyl esters of C.sub.2- to C.sub.18-monocarboxylic acids,
C.sub.1- to C.sub.12-esters of unsaturated monocarboxylic acids or
unsaturated .alpha.,.beta.-dicarboxylic acids, or the esters or
anhydrides thereof. Onto this are grafted homo- or copolymers of
alkyl acrylates, the alkyl group thereof having at least 12 carbon
atoms and at least 20% of the alkyl groups having at least 22
carbon atoms. The graft reaction can be effected in aliphatic or
aromatic solvents, preferably in toluene, xylene or aromatic
solvent fractions. In the examples, xylene is used as the
solvent.
[0013] Commercially available graft copolymer formulations composed
of ethylene-vinyl acetate copolymers and polyacrylates which have
long alkyl chains and have been (partly) grafted thereon for use as
paraffin inhibitors or pour point depressants are frequently
supplied as highly concentrated solutions in toluene. However, a
disadvantage of these is that the flashpoint of toluene is only
about 6.degree. C. This comparatively low flashpoint complicates
the handling of the products, for example in a refinery or on an
offshore platform, because appropriate safety measures have to be
taken when working with the formulation. There is therefore a
demand in the market for pour point depressants formulated in
solvents having a flashpoint of at least 60.degree. C.
[0014] The use of other solvents, however, is by no means
unproblematic, since, for economic reasons, the graft copolymers
should not be isolated from the solvents such as toluene used for
the synthesis and formulated for use in suitable solvents only in a
second step; instead, the formulations obtained in the course of
production should be usable directly, without isolating the
polymer. Typical use concentrations of pour point depressants of,
for example, 500 ppm appear to be small. This number means,
however, that 0.5 kg of pour point depressant has to be used per t
of crude oil. Global oil production in 2011 was about 4 billion t.
Pour point depressants are therefore not small-volume specialty
products but products which have to be produced inexpensively in
large volumes.
[0015] Naturally, the choice of solvent for a polymerization has a
quite considerable influence on the polymerization process. If, for
example, toluene is replaced by higher-boiling alkylaromatics, for
example cumene, this can influence the chain transfer rate and
hence the molecular weight of the resulting polymer in the
free-radical polymerization.
[0016] Moreover, the choice of solvent naturally influences the
dissolution characteristics of the polymers. Pour point depressants
are generally supplied as concentrated solutions and can be
formulated for use in the desired manner by the users on site. The
products supplied should be liquid in order to avoid melting on
site, and the solutions should also remain stable over a long
period and not have a tendency to phase separation, such that they
can be stored with great simplicity.
[0017] It was therefore an object of the invention to provide a
process for producing pour point depressants from ethylene-vinyl
acetate copolymers and alkyl acrylates in solvents having a
flashpoint of at least 60.degree. C., and the formulations were to
have at least the same influence on the pour point as conventional
products produced in toluene. It was to be possible to add the
formulations in a simple and safe manner to crude oils, and the
solutions were to have adequate stability.
[0018] Accordingly, a process has been found for producing a
polymer formulation at least comprising two different solvents and
[0019] a polymeric composition obtainable by free-radical
polymerization of at least one monoethylenically unsaturated
monomer (A) in the presence of at least one ethylene-vinyl ester
copolymer (B), [0020] the monomers (A) comprising at least 70% by
weight--based on the amount of all monomers (A)--of at least one
alkyl (meth)acrylate (A1) of the general formula
H.sub.2C=CR.sup.1-COOR.sup.2where R.sup.1 is H or a methyl group
and R.sup.2 is a linear alkyl radical having 12 to 60 carbon atoms,
[0021] the ethylene-vinyl ester copolymers (B) comprising 55 to 85%
by weight of ethylene and 15 to 45% by weight of vinyl esters of
the general formula H.sub.2C=CH-O-(O)C-R.sup.3 (III) where R.sup.3
is H or a C.sub.1- to C.sub.4 hydrocarbyl radical, and [0022] the
amount of the monomers (A) being 70 to 90% by weight and that of
the ethylene-vinyl ester copolymers (B) 10 to 30% by weight based
on the sum of the monomers (A) and the ethylene-vinyl ester
copolymers (B) together, [0023] and the solvents comprising at
least [0024] a nonpolar solvent (S1) comprising saturated aliphatic
hydrocarbyl groups and having a flashpoint .gtoreq.60.degree. C.,
and [0025] an aromatic hydrocarbon (S2) having a flashpoint
.gtoreq.60.degree. C., [0026] and the process comprising at least
the following process steps: [0027] (I) providing a solution at
least comprising monomers (A) and ethylene-vinyl ester copolymers
(B) each in the abovementioned amounts in at least one solvent
(S1), and [0028] (II) free-radically polymerizing the monomers (A)
in the presence of the ethylene-vinyl ester copolymers (B) by
addition of at least one thermally decomposing initiator for the
free-radical polymerization to the solution obtained in (II) and
polymerizing at a temperature of at least 50.degree. C., the
reaction medium being diluted with solvents (S2) during and/or
after the polymerization.
[0029] The solvents (S1) are preferably saturated aliphatic
hydrocarbons having a flashpoint .gtoreq.60.degree. C.
[0030] The solution of the monomers (A1) is preferably provided in
two stages in process step (I), by first esterifying at least one
alcohol of the general formula R.sup.2-OH with (meth)acrylic acid
H.sub.2C=CR.sup.1-COOH in the presence of solvents (S1) and then
mixing the solution formed with at least one ethylene-vinyl ester
copolymer (B).
[0031] In a second aspect of the invention, polymer formulations
have been found, at least comprising [0032] two different solvents
and [0033] a polymeric composition obtainable by free-radical
polymerization of at least one monoethylenically unsaturated
monomer (A) in the presence of at least one ethylene-vinyl ester
copolymer (B), [0034] the monomers (A) comprising at least 70% by
weight--based on the amount of all monomers (A)--of at least one
alkyl (meth)acrylate (A1) of the general formula
H.sub.2C=CR.sup.1-COOR.sup.2 where R.sup.1 is H or a methyl group
and R.sup.2 is a linear alkyl radical having 12 to 60 carbon atoms,
[0035] the ethylene-vinyl ester copolymers (B) comprising 55 to 85%
by weight of ethylene and 15 to 45% by weight of vinyl esters of
the general formula H.sub.2C=CH-O-(O)C-R.sup.3 (III) where R.sup.3
is H or a C.sub.1- to C.sub.4 hydrocarbyl radical, and [0036] the
amount of the monomers (A) being 70 to 90% by weight and that of
the ethylene-vinyl ester copolymers (B) 10 to 30% by weight based
on the sum of the monomers (A) and the ethylene-vinyl ester
copolymers (B) together, [0037] the solvents comprising at least
[0038] a nonpolar solvent (S1) comprising saturated aliphatic
hydrocarbyl groups and having a flashpoint .gtoreq.60.degree. C.,
and [0039] an aromatic hydrocarbon (S2) having a flashpoint
.gtoreq.60.degree. C.
[0040] In a third aspect, the use of the polymer formulation as a
pour point depressant for crude oil, mineral oil and/or mineral oil
products has been found, by adding at least said polymer
formulation to the crude oil, mineral oil and/or mineral oil
products.
[0041] Specific Details of the Invention are as Follows:
[0042] Starting Materials Used
[0043] Solvents S1
[0044] To execute the invention, at least one nonpolar solvent (S1)
comprising saturated aliphatic hydrocarbyl groups and having a
flashpoint .gtoreq.60.degree. C. is used. It is of course also
possible to use a mixture of different solvents (S1).
[0045] The solvents (S1) should be nonpolymerizable and have no
significant regulating action, if any, in the course of
free-radical polymerization. Examples of suitable solvents comprise
saturated aliphatic hydrocarbons, saturated aliphatic alcohols or
esters of saturated aliphatic carboxylic acids and saturated
aliphatic alcohols, with the proviso that the solvents each have a
flashpoint .gtoreq.60.degree. C. Examples of alcohols comprise
aliphatic alcohols having at least 8 carbon atoms, such as
1-octanol, 1-decanol or 1-dodecanol. Examples of esters comprise
esters of saturated fatty acids having at least 8 carbon atoms with
saturated aliphatic alcohols, for example methyl laurate or methyl
stearate. Technical mixtures of various aliphatic esters are
commercially available. In a further embodiment of the invention,
it is possible to use esters of aliphatic or cycloaliphatic
dicarboxylic acids, for example dialkyl esters of
cyclohexane-1,2-dicarboxylic acid, such as diisononyl
cyclohexane-1,2-dicarboxylate.
[0046] In a preferred embodiment of the invention, the solvents
(S1) are saturated aliphatic solvents or solvent mixtures having a
flashpoint .gtoreq.60.degree. C. These may be either paraffinic or
naphthenic, i.e. saturated cyclic, hydrocarbons. Saturated
aliphatic hydrocarbons having a flashpoint 60.degree. C. are
high-boiling and typically have a boiling point of at least
175.degree. C. Examples of suitable hydrocarbons comprise
n-undecane (flashpoint 60.degree. C., boiling point 196.degree. C.)
or n-dodecane (flashpoint 71.degree. C., boiling point 216.degree.
C.). It is possible with preference to use technical mixtures of
hydrocarbons, for example mixtures of paraffinic hydrocarbons,
mixtures of paraffinic and naphthenic hydrocarbons or mixtures of
isoparaffins. It will be apparent to those skilled in the art that
technical mixtures may still comprise small residues of aromatic or
unsaturated hydrocarbons. The content of aromatic and/or
unsaturated hydrocarbons should, however, be generally <1% by
weight, preferably <0.5% by weight and more preferably <0.1%
by weight. Technical mixtures of saturated aliphatic solvents are
commercially available, for example technical mixtures of the
Shellsol.RTM. D series or the Exxsol.RTM. D series.
[0047] It is of course also possible to use mixtures of various
solvents (S1). In a preferred embodiment of the invention, the
solvents (S1) are exclusively saturated aliphatic solvents or
solvent mixtures.
[0048] Aromatic Solvents S2
[0049] To execute the invention, in addition, aromatic solvents or
solvent mixtures having a flashpoint .gtoreq.60.degree. C. (S2) are
used. Such hydrocarbons are high-boiling and typically have a
boiling point of at least 175.degree. C. In principle, it is
possible to use any aromatic hydrocarbons having a flashpoint
.gtoreq.60.degree. C., for example naphthalene. It is possible with
preference to use technical mixtures of aromatic hydrocarbons.
Technical mixtures of aromatic solvents are commercially available,
for example technical mixtures of the Shellsol.RTM. A series or the
Solvesso.RTM. series.
[0050] Monomers (A)
[0051] The monomers (A) used are monoethylenically unsaturated
monomers, with the proviso that at least 70% by weight thereof are
alkyl (meth)acrylates (A1) of the general formula
H.sub.2C=CR.sup.1-COOR.sup.2. In this formula, where R.sup.1 is H
or a methyl group, preferably H, and R.sup.2 is a linear alkyl
radical having 12 to 60 carbon atoms, preferably 16 to 30 carbon
atoms, more preferably 18 to 24 carbon atoms and, for example, 18
to 22 carbon atoms. It will be appreciated that it is possible to
use mixtures of various alkyl (meth)acrylates (A1). For example, it
is possible to use mixtures in which R.sup.2 represents C.sub.16
and C.sub.18 radicals or C.sub.18, C.sub.20 and C.sub.22
radicals.
[0052] As well as the monomers (A1), it is possible to use further
monomers (A) other than the monomers (A1). With the aid of further
monomers (A) as well as the monomers (A1), it is possible to modify
the properties of the inventive formulations and match them to the
desired properties. The person skilled in the art makes a suitable
selection. The selection is limited only by the fact that further
monomers (A) have to be miscible with the solvents (S1) and the
monomers (A1) at the use concentration selected.
[0053] Further monomers (A) may especially be (meth)acrylates which
do not correspond to the above definition of the monomers (A1),
vinyl esters, vinyl ethers, vinylamides or vinylamines.
[0054] In one embodiment of the invention, further monomers (A) are
(meth)acrylates (A2) of the general formula
H.sub.2C=CR.sup.1-COOR.sup.4 where R.sup.1 is H or methyl and
R.sup.4 is at least one hydrocarbyl radical selected from the group
of R.sup.4a, R.sup.4b, R.sup.4c and R.sup.4d radicals, where the
radicals are each defined as follows: [0055] R.sup.4a: linear alkyl
radicals having 1 to 11, preferably 2 to 10, carbon atoms, [0056]
R.sup.4b; branched alkyl radicals having 4 to 60, preferably 4 to
30, more preferably 4 to 17, carbon atoms, [0057] R.sup.4c:
unsubstituted or alkyl-substituted saturated cyclic hydrocarbyl
radicals having 5 to 30, preferably 6 to 17, carbon atoms, or
[0058] R.sup.4d: unsubstituted or alkyl-substituted aromatic
hydrocarbyl radicals having 6 to 30, preferably 6 to 18, carbon
atoms.
[0059] Examples of linear alkyl radicals R.sup.4a comprise ethyl,
n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl,
n-decyl and n-undecyl radicals, preference being given to n-propyl,
n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl and n-decyl
radicals.
[0060] Examples of branched alkyl radicals R.sup.4b comprise
i-butyl, t-butyl, 2,2'-dimethylpropyl, 2-ethylhexyl,
2-propylheptyl, i-nonanol, i-decyl, i-tridecyl, i-heptadecyl
radicals, preference being given to t-butyl, 2-ethylhexyl and
3-propylheptyl radicals.
[0061] An example of a cyclic alkyl radical R.sup.4c is a
cyclohexyl radical.
[0062] Examples of aromatic hydrocarbyl radicals R.sup.4d comprise
phenyl, 4-methylphenyl, benzyl or 2-phenylethyl radicals.
[0063] In a further embodiment of the invention, further monomers
(A) are (meth)acrylates (A3) of the general formula
H.sub.2C=CR.sup.1-COOR.sup.5 where R.sup.1 is H or methyl and
R.sup.5 is a linear or branched, aliphatic and/or aromatic
hydrocarbyl radical which has 1 to 60, preferably 2 to 30, carbon
atoms and may be substituted by OH groups and/or in which
nonadjacent carbon atoms may be substituted by oxygen atoms. In
other words, R.sup.3 radicals may thus comprise OH groups and/or
ether groups --O--. Examples of (meth)acrylates (A3) comprise
hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate,
phenoxyethyl acrylate, or polypropylene glycol
mono(meth)acrylate.
[0064] In a further embodiment of the invention, further monomers
(A) are vinyl esters of the general formula
H.sub.2C=C-O-(O)C-R.sup.5(A4) where R.sup.6 is a linear or branched
alkyl radical having 1 to 60 carbon atoms, preferably 2 to 30
carbon atoms. Examples of R.sup.6 radicals comprise methyl, ethyl,
n-propyl or n-butyl radicals.
[0065] In a preferred embodiment of the invention, further monomers
(A) are at least one monomer (A2), preferably those having an
R.sup.4b radical, especially R.sup.4b) radicals having 4 to 17
carbon atoms. Examples of preferred monomers (A2) comprise t-butyl
(meth)acrylate, 2-ethylhexyl (meth)acrylate and 2-propylheptyl
(meth)acrylate, particular preference being given to t-butyl
(meth)acrylate.
[0066] According to the invention, the amount of the alkyl
(meth)acrylates (A1) based on the total amount of all monomers (A)
is at least 70% by weight, preferably at least 85% by weight, more
preferably at least 95% by weight, and the monomers (A) used are
most preferably exclusively alkyl (meth)acrylates (A1).
[0067] In one embodiment of the invention, the monomers (A) used
are a mixture of alkyl (meth)acrylates (A1) and alkyl
(meth)acrylates (A2), for example a mixture of 70 to 99% by weight
of monomers (A1) and 1 to 30% by weight of monomers (A2),
preferably a mixture of 70 to 95% by weight of monomers (A1) and 5
to 30% by weight of monomers (A2).
[0068] Ethylene-vinyl Ester Copolymers (B)
[0069] The ethylene-vinyl ester copolymers (B) used comprise
ethylene and vinyl esters of the general formula
H2C=CH-O-(O)C-R.sup.3. In this formula, R.sup.3 is H or a C.sub.1-
to C.sub.4-hydrocarbyl radical, for example a methyl, ethyl,
n-propyl or n-butyl radical. R.sup.3 is preferably H, methyl or
ethyl and more preferably methyl.
[0070] As well as ethylene and the vinyl esters, further monomers
may optionally also be present. The amount of such further monomers
should, however, not exceed 20% by weight, preferably 10% by
weight, based on the amount of all monomers, and particular
preference is given to the presence of no further monomers aside
from ethylene and the vinyl esters.
[0071] The amount of ethylene in the ethylene-vinyl ester
copolymers (B) is 55 to 85% by weight and the amount of vinyl
esters is 15 to 45% by weight based on the amount of all
monomers.
[0072] Preferably, the amount of ethylene is 55 to 75% by weight
and the amount of vinyl esters 25 to 45% by weight, more preferably
30 to 40% by weight, and, most preferably, the amount of ethylene
is 60 to 70% by weight and the amount of vinyl esters 30 to 40% by
weight.
[0073] The weight-average molecular weight M.sub.w of the
ethylene-vinyl ester copolymers (B) used is preferably at least 30
000 g/mol, for example 30 000 g/mol to 200 000 g/mol, preferably 50
000 g/mol to 150 000 g/mol.
[0074] Process step (I)--Provision of a Solution of the Starting
Materials for the Polymerization
[0075] In process step (I), a solution at least comprising the
monomers (A) and an ethylene-vinyl ester copolymer (B) in at least
one solvent (S1) is provided. According to the invention, the
monomers (A) comprise at least 70% by weight of at least one alkyl
(meth)acrylate (A1) and optionally further different monomers
(A).
[0076] This can be effected by dissolving the monomers (A),
including at least 70% by weight of alkyl (meth)acrylates (A1), and
at least one ethylene-vinyl ester copolymer (B) in at least one
solvent (S1). This can be effected by mixing solid ethylene-vinyl
ester copolymer (B), the monomers (A), including the alkyl
(meth)acrylates (A1), vigorously with the solvents (S1), for
example by stirring. The dissolution can be accelerated by
increasing the temperature, for example to about 50 to 80.degree.
C. Alternatively, the monomers (A) and the ethylene-vinyl ester
copolymer (B) can each be dissolved separately in solvents (S1) and
the solutions obtained can be mixed with one another. It will be
appreciated that further variants for the mixing are also
possible.
[0077] The mixing ratio of monomers (A) and ethylene-vinyl ester
copolymers (B) is selected according to the desired properties of
the polymeric composition to be synthesized, and the amount of the
monomers (A) should be at least 50% by weight based on the sum of
monomers A and ethylene-vinyl ester copolymers B. In general, the
amount of the monomers (A) is 70 to 90% by weight and that of the
ethylene-vinyl ester copolymers (B) 10 to 30% by weight.
Preferably, the amount of the monomers (A) is 75 to 85% by weight
and that of the ethylene-vinyl ester copolymers (B) 15 to 25% by
weight.
[0078] The resulting solution of alkyl (meth)acrylates (Al1,
optionally further monomers (A), for example further monomers (A2),
(A3) and/or (A4), and ethylene-vinyl ester copolymers (B) in
solvents (S1) is used for process step (II).
[0079] Two-Stage Process for Providing the Solution of the Monomers
(A)
[0080] In a preferred embodiment of process step (I), the solution
is provided in a two-stage process comprising process steps (Ia)
and (Ib).
[0081] Process Step (Ia)
[0082] In process step (Ia), a solution of alkyl (meth)acrylates
(Al) of the general formula H2C=CR.sup.1- COOR.sup.2 in solvents
(S1) is prepared by esterifying at least one alcohol of the general
formula R.sup.2-OH with (meth)acrylic acid H.sub.2C=CR.sup.1-COOH
in the presence of solvents (S1), where the R.sup.1 and R.sup.2
radicals are each as defined above. Preference is given to acrylic
acid.
[0083] The alcohols R.sup.2-OH used for esterification may be
defined linear alcohols. Examples comprise hexadecan-1-ol (cetyl
alcohol), octadecan-1-ol (stearyl alcohol), nonadecan-1-ol,
eicosan-1-ol (arachyl alcohol), heneicosan-1-ol, docosan-1-ol
(behenyl alcohol), tetracosan-1-ol, hexacosan-1-ol, octacosan-1-ol
or tricontan-1-ol. It is advantageously also possible to use
technical mixtures of various linear alcohols, which may be fatty
alcohols or synthetic alcohols. Examples of preferred mixtures
comprise mixtures of C.sub.16/C.sub.18 alcohols (tallow fat
alcohols) or mixtures of C.sub.18/C.sub.20/C.sub.22 alcohols, and
such mixtures may of course also comprise further alcohols as
secondary components in small amounts.
[0084] According to the invention, the esterification is performed
in saturated aliphatic hydrocarbons as solvents (S1). Details of
saturated aliphatic hydrocarbons and hydrocarbon mixtures and
preferred saturated aliphatic hydrocarbons and hydrocarbon mixtures
have already been given above. The amount of the hydrocarbons is
preferably selected here such that the concentration of the alkyl
(meth)acrylates A1 formed in the saturated aliphatic hydrocarbons
after the end of the esterification is 40 to 90% by weight, more
preferably 50 to 85% by weight, based on the sum of all components
of the solution.
[0085] The esterification can be performed by methods known in
principle to those skilled in the art, for example by the processes
described by EP 486 836 A1. The esterification can be performed
using customary acidic esterification catalysts such as sulfuric
acid, p-toluenesulfonic acid, methanesulfonic acid or acidic ion
exchangers. It is additionally advisable to use polymerization
inhibitors, for example hydroquinone derivatives or
4-methoxyphenol. The esterification can be undertaken in a manner
known in principle by heating the mixture, preferably to a
temperature >100.degree. C., for example 100.degree. C. to
160.degree. C., with distillative removal of water of reaction
formed. Saturated aliphatic hydrocarbons distilled off as well as
the water can be separated from water in a customary manner in
water separators. The hydrocarbons can be recycled into the
reaction mixture.
[0086] Process Step (Ib)
[0087] The solution of alkyl (meth)acrylates (A1) in solvents (S1)
provided in process step (Ia) is mixed in process step (Ib) with at
least one ethylene-vinyl ester copolymer (B). It is of course also
possible to use a mixture of several different ethylene-vinyl ester
copolymers (B). It is optionally also possible for further monomers
(A) to be present in the mixture in process step (II). Process step
(Ib) is preferably performed in the same apparatus in which process
step (II) is also performed.
[0088] Process Step (II)--Free-Radical Polymerization
[0089] In process step (II), the monomers (A) dissolved in the
solvents (S1), comprising at least 75% by weight of monomers (A1),
are free-radically polymerized in the presence of the
ethylene-vinyl ester copolymers (B).
[0090] The free-radical polymerization is performed by adding at
least one thermal initiator for free- radical polymerization to the
solution obtained in process step (I). Naturally, the initiators
used are selected such that they are soluble in the polymerization
medium. Preferred polymerization initiators comprise oil-soluble
azo compounds, especially those having a 10 h half-life of
50.degree. C. to 70.degree. C. Examples of suitable initiators
comprise dimethyl 2,2'-azobis(2-methylpropionate) (10 h half-life
approx. 66.degree. C.), 2,2'-azobis(2-methylbutyronitrile) (10 h
half-life approx. 67.degree. C.) or 2,2'-
azobis(2,4-dimethylvaleronitrile) (10 h half-life approx.
51.degree. C.). Such initiators are commercially available (from
Wako). The weight ratio of monomers (A) to the initiators is
generally about 100:1 to 150:1, preferably 125:1 to 140:1. It is
possible for the entire amount of the initiators to be present at
the start of the polymerization, but preference is given to adding
the initiator gradually. The addition may be in portions or
continuous, preferably continuous.
[0091] For use in the polymerization, the polymerization initiators
are preferably dissolved in solvents (S1) and/or solvents (S2) and
the solution can be added to the reaction mixture.
[0092] In addition, molecular weight regulators can be added in a
manner known in principle. Examples of regulators comprise alcohols
such as isopropanol, allyl alcohol or buten-2-ol, thiols such as
ethanethiol, or aldehydes such as crotonaldehyde. The amount of the
molecular weight regulators is generally 1 to 4% by weight based on
the monomers (A), preferably 2 to 3% by weight based on the
monomers (A).
[0093] The free-radical polymerization is triggered in a manner
known in principle by heating the reaction mixture. The
polymerization temperature should be above the 10 h half-life of
the initiator and is generally at least 50.degree. C. A useful
polymerization temperature has been found to be from 50 to
90.degree. C. In general, the polymerization is undertaken in a
manner known in principle under a protective gas such as nitrogen
or argon.
[0094] The polymerization can be undertaken by initially charging
the solution obtained in process step (I) in a suitable, typically
stirred reaction vessel, process step (II) advantageously being
performed actually in the same apparatus as process step (I) or
(Ib). If desired, one or more molecular weight regulators are added
to the solution. After the desired polymerization temperature has
been attained, a solution of the polymerization initiator is added
gradually to the mixture to be polymerized. The duration of
addition may be 0.5 h to 10 h, without any intention to restrict
the invention to this range. The completion of addition of the
initiator should generally be followed by a further polymerization
time. This may, for example, be 0.5 to 5 h. It will be appreciated
that the initiator can also be added prior to the heating.
[0095] According to the invention, the reaction medium is diluted
with solvents (S2) during and/or after the polymerization.
[0096] The expression "after the polymerization" means that the
addition is effected once the polymerization is complete or has at
least substantially ended, but the reaction mixture has not yet
cooled completely from the polymerization temperature to room
temperature. It is generally effected in the apparatus used for
polymerization. Preferably, an addition "after the polymerization"
immediately follows the polymerization, at a time when the
temperature of the reaction medium has not yet fallen, or has not
yet fallen more than 20.degree. C., preferably not more than
10.degree. C., below the reaction temperature at the end of the
polymerization.
[0097] In a preferred embodiment of the invention, a portion of the
solvents (S2) is added during the polymerization and a portion of
the solvents (S2) thereafter. In one embodiment of the invention, 1
to 40% by weight, preferably 5 to 30% by weight, of the total
amount of solvents S2 used is added during the polymerization, and
the rest after the polymerization.
[0098] The addition of the aromatic solvents (S2) during the
polymerization can be effected, for example, by dissolving the
polymerization initiators in solvents (S2) and adding the solution
gradually.
[0099] Instead of or in addition to this embodiment, a portion of
the solvent (S2) can be added after addition of a portion of the
initiator. Such an addition can be effected, for example, after
addition of 40 to 70% of the initiator, and this addition may be 1
to 40% by weight, preferably 5 to 30% by weight, of the total
amount of solvents (S2).
[0100] The weight ratio of the saturated aliphatic solvents to the
aromatic solvents S1/S2 is generally 1:5 to 2:1.
[0101] The concentration of the monomers A in the solvents (S1) at
the start of process step (II) is selected by the person skilled in
the art according to the desired properties of the formulation to
be produced. In a preferred embodiment of the invention, the
concentration is 50 to 85% by weight. Such a concentrate has the
advantage that the transport costs from the site of production to
the site of use, for example an oil production installation, can be
kept low.
[0102] The amount of the solvents (S1) and (S2) together is
likewise selected according to the desired properties. In a
preferred embodiment, it is such that the concentration of all
polymers prepared together at the end of process step (II) is 40 to
50% by weight based on the sum of all components of the
solution.
[0103] By means of the process described, a polymeric composition
in a mixture of solvents (S1) and (S2) is obtainable. The
polymerization of the monomers (A) in the presence of the
ethylene-vinyl ester copolymers (B) prevents the polymer components
from separating from one another. The result of the polymerization
reaction is different when the monomers (A)--under otherwise
identical conditions--are polymerized separately from the
ethylene-vinyl ester copolymers (B) and the solution of the polymer
formed from the monomers (A) and the ethylene-vinyl ester
copolymers (B) are combined after the polymerization. Such
solutions can separate again.
[0104] Although we do not wish to be bound to a particular theory,
this effect can be explained by at least partial grafting of the
monomers (A) onto the ethylene-vinyl ester copolymer (B) in the
course of polymerization. A further portion of the monomers may
polymerize without being grafted on. This gives rise to
ethylene-vinyl ester graft copolymers with side groups comprising
monomers (A), and homo- or copolymers comprising monomers (A). In a
manner known in principle, the partial grafting prevents separation
of the two polymer components. It is also possible that no
significant grafting occurs, but that an "interjacent complex"
forms from the ethylene-vinyl ester copolymers (B) and the homo- or
copolymers of monomers (A). In such a complex, the polymers are
predominantly physically bound and nevertheless stable, as
described, for example, in U.S. Pat. No. 7,001,903 B2.
Formulations
[0105] The inventive polymer formulation comprises at least [0106]
two different solvents and [0107] a polymeric composition
obtainable by free-radical polymerization of at least one
monoethylenically unsaturated monomer (A) in the presence of at
least one ethylene-vinyl ester copolymer (B), [0108] the monomers
(A) comprising at least 70% by weight--based on the amount of all
monomers (A)--of at least one alkyl (meth)acrylate (A1) of the
general formula H.sub.2C=CR.sup.1-COOR.sup.2where R.sup.1 is H or a
methyl group and R.sup.2 is a linear alkyl radical having 12 to 60
carbon atoms, [0109] the ethylene-vinyl ester copolymers (B)
comprising 55 to 85% by weight of ethylene and 15 to 45% by weight
of vinyl esters of the general formula H.sub.2C=CH-O-(O)C-R.sup.3
(III) where R.sup.3 is H or a C.sub.1- to C.sub.4 hydrocarbyl
radical, and [0110] the amount of the monomers (A) being 70 to 90%
by weight and that of the ethylene-vinyl ester copolymers (B) 10 to
30% by weight based on the sum of the monomers (A) and the
ethylene-vinyl ester copolymers (B) together, [0111] the solvents
comprising at least [0112] a nonpolar solvent (S1) comprising
saturated aliphatic hydrocarbyl groups and having a flashpoint
.gtoreq.60.degree. C., and [0113] an aromatic hydrocarbon (S2)
having a flashpoint .gtoreq.60.degree. C.
[0114] Preferred embodiments, for example with regard to the type
of monomers (A), copolymers (B), and the amounts and mixing ratios
thereof, have already been detailed above.
[0115] In a preferred embodiment of the invention, the weight ratio
of the aliphatic solvents to the aromatic solvents S1/S2 is 1:5 to
2:1.
[0116] In a further preferred embodiment of the invention, the
concentration of all polymers together is 40 to 50% by weight based
on the sum of all constituents of the solution.
[0117] In a further preferred embodiment of the invention, the
polymer formulation is obtainable by means of the process detailed
above.
[0118] Use of the Formulations as a Pour Point Depressant
[0119] The above-detailed polymer formulations in hydrocarbons (S1)
and (S2), especially the polymer formulations obtainable by means
of the process according to the invention, can be used in
accordance with the invention as pour point depressants for crude
oil, mineral oil and/or mineral oil products, by adding at least
one of the polymer formulations detailed to the crude oil, mineral
oil and/or mineral oil products. In addition, it is of course also
possible to use further formulations which act as pour point
depressants.
[0120] Pour point depressants reduce the pour point of crude oils,
mineral oils and/or mineral oil products. The pour point ("yield
point") refers to the lowest temperature at which a sample of an
oil, in the course of cooling, still just flows. For the
measurement of the pour point, standardized test methods are
used.
[0121] For the inventive use, the abovementioned concentrate, for
example a concentrate with a total polymer content of 50% by weight
to 80% by weight, can be used as such. However, it is also possible
to dilute with further solvent, preferably with solvents (S1)
and/or (S2), and/or to formulate it with further components. For
example, additional wax dispersants can be added to the
formulation. Wax dispersants stabilize paraffin crystals which have
formed and prevent them from sedimenting. The wax dispersants used
may, for example, be alkylphenols, alkylphenol-formaldehyde resins
or dodecylbenzenesulfonic acid. The concentration of a usable
formulation may, for example, be 20 to 50% by weight, preferably 25
to 40% by weight, of polymers prepared in accordance with the
invention and optionally further components except for the
solvents, this figure being based on the total amount of all
components including the solvents. While the inventive formulations
are naturally typically produced in a chemical plant, the
ready-to-use formulation can advantageously be produced on site,
i.e., for example, directly at a production site for oil.
[0122] The inventive use is effected by adding the inventive
formulations optionally comprising further components and/or dilute
formulations to the crude oil, mineral oil and/or mineral oil
products, preferably to the crude oil.
[0123] The formulations are typically used in such an amount that
the amount of the polymeric composition added is 50 to 1500 ppm
based on the oil. The amount is preferably 100 to 1000 ppm, more
preferably 250 to 600 ppm and, for example, 300 to 600 ppm. The
amounts are based on the polymeric composition not including the
solvents (S1) and (S2) and optional further components of the
formulation.
[0124] In a preferred embodiment of the invention, the oil is crude
oil and the formulation is injected into a crude oil pipeline. The
injection can preferably be effected at the oilfield, i.e. at the
start of the crude oil pipeline, but the injection can of course
also be effected at another site. More particularly, the pipeline
may be one leading onshore from an offshore platform. Explosion
protection is particularly important on offshore platforms and in
refineries, and the inventive formulations based on solvents having
a flashpoint .gtoreq.60.degree. C. accordingly simplify working
quite considerably. Moreover, the cooling of crude oil in
underwater pipelines leading onshore from an offshore platform is
naturally particularly rapid, especially when the pipelines are in
cold water, for example having a water temperature of less than
10.degree. C.
[0125] In a further preferred embodiment of the invention, the oil
is crude oil and the formulation is injected into a production
well. Here too, the production well may especially be a production
well leading to an offshore platform. The injection is preferably
effected approximately at the site where oil from the formation
flows into the production well. In this way, the solidification of
the crude oil in the production well or an excessive increase in
its viscosity can be prevented.
[0126] Further Uses of the Formulations
[0127] The inventive formulation can of course also be used for
other purposes.
[0128] In a further embodiment of the invention, the above-detailed
polymer formulations in hydrocarbons (S1) and (S2), especially the
polymer formulations obtainable by means of the process according
to the invention, are used to prevent wax deposits on surfaces in
contact with crude oil, mineral oil and/or mineral oil products.
The use is effected by adding at least one of the polymer
formulations detailed to the crude oil, mineral oil and/or mineral
oil products. Preferred formulations have already been mentioned,
and the manner of use is also analogous to the use as a pour point
depressant. In addition, it is of course also possible to use
further formulations which act as wax inhibitors.
[0129] The following examples are intended to illustrate the
invention in detail:
[0130] A Production of the Polymer Formulations Used
[0131] In the examples, the polymer formulations are produced in a
two-stage process. In the first stage, acrylic acid is esterified
with the desired alcohol in a solvent. In the second stage, the
resulting solution of the alkyl acrylates is used without further
purification and is reacted with an ethylene-vinyl acetate
copolymer to give a graft copolymer in which the polyacrylates are
at least partly grafted onto the ethylene-vinyl acetate copolymer.
The product obtained may, as well as the graft copolymer, also
comprise as yet ungrafted polyacrylates. For use, the products
remain dissolved in the solvents in which they were dissolved in
the synthesis.
[0132] Starting Materials Used:
TABLE-US-00001 Shellsol .RTM. D70 high-boiling aliphatic
hydrocarbon mixture from Shell Chemicals, essentially composed of
C.sub.11 to C.sub.14 aliphatics (approx. 60% paraffins, approx. 40%
cycloparaffins, aromatics content < 100 ppm), initial boiling
point to ASTM D 86 198.degree. C., flashpoint to ASTM D93
74.degree. C. Solvesso .RTM. 150 high-boiling aromatic hydrocarbon
mixture from ExxonMobil Chemical Company, aromatics content >
99% by vol., initial boiling point 181.degree. C., flashpoint to
ASTM D93 66.degree. C. Solvesso .RTM. 150 ND high-boiling aromatic
hydrocarbon mixture from ExxonMobil Chemical Company, aromatics
content > 99% by vol., initial boiling point 184.degree. C.,
flashpoint to ASTM D93 65.degree. C. ethylene-vinyl acetate
ethylene-vinyl acetate copolymer formed from 67% by weight of
copolymer ethylene and 33% by weight of vinyl acetate, melt flow
index 21 g/10 min (measured to ASTM D 1238), M.sub.n approx. 34 000
g/mol, M.sub.w approx. 134 000 g/mol. Nafol .RTM. 1822 mixture of
linear aliphatic alcohols from Sasol (C.sub.16 .ltoreq. 1% by
weight, C.sub.18 43 +/- 2% by weight, C.sub.20 11 +/- 2% by weight,
C.sub.22 44 +/- 2% by weight, C.sub.24 .ltoreq. 1% by weight)
Hydrenol .RTM. D tallow fat alcohol, mixture of linear aliphatic
alcohols from Sasol (<C.sub.16 0 to 0.6% by weight, C.sub.16 30
+/- 5% by weight C.sub.18, C.sub.18 65 +/- 2% by weight,
>C.sub.18 0 to 3% by weight). Wako V-601 dimethyl
2,2'-azoisobutyrate, 10 h half-life approx. 66.degree. C. (in
toluene)
[0133] Polymer 1
[0134] Stage 1
[0135] A reactor with stirrer, water separator, jacketed coil
condenser and gas inlet tube is initially charged with 1888.2 g of
C.sub.16/18 tallow fat alcohol (Hydrenol.RTM. D), 5.6 g of
p-toluenesulfonic acid, 3.6 g of 4-methoxyphenol and 541.1 g of a
commercially available high-boiling aliphatic solvent mixture
(Shellsol.RTM. D70). The water separator is charged with 35 g of
Shellsol.RTM. D70. The reaction mixture is purged with lean air (6%
O.sub.2) and heated to 80.degree. C. while stirring (50 rpm) in
order to dissolve the C.sub.16/18 tallow fat alcohol. After
increasing the stirrer speed to 250 rpm, 519.1 g of acrylic acid
are metered in and the temperature is increased to a maximum of
165.degree. C., such that water of reaction formed can be distilled
off. After 8 to 10 h, the reaction is ended. A solution of
1-hexadecyl acrylate and 1-octadecyl acrylate in Shellsol.RTM. D70
is obtained (concentration 80% by weight of acrylates).
[0136] Stage 2
[0137] In a four-neck flask with Teflon stirrer, jacketed coil
condenser and Dosimat, 424.5 g of the monomer solution (80% by
weight of acrylates) are heated to 75.degree. C. while stirring
(300 rpm) under an N.sub.2 blanket, and 84.0 g of the
abovementioned ethylene-vinyl acetate copolymer are added and
dissolved. Then 9.2 g of Shellsol.RTM. D70 are added. After adding
6.9 g of allyl alcohol, 1.8 g of the initiator dimethyl
2,2'-azoisobutyrate (Wako V-601) dissolved in 29.5 g of a high-
boiling aliphatic solvent (Shellsol.RTM. D70) are metered in at an
internal temperature of 72.degree. C. over 3 hours. In order to
counteract the rise in viscosity and the rise in temperature, after
half of the initiator has been added, the mixture is diluted with
50.0 g of Solvesso.RTM. 150 ND. After further polymerization at
72.degree. C. for 2.5 hours, the mixture is diluted with 270.1 g of
Solvesso.RTM. 150 ND and stirred for 30 min, before being filtered
through a 400 .mu.m fast sieve.
[0138] A solution is obtained which comprises 50% by weight of
graft copolymers (approx. 20% by weight of ethylene-vinyl acetate
copolymer and approx. 80% by weight of polyacrylate, based in each
case on the graft copolymer), 10% by weight of high-boiling
aliphatic solvent having a flashpoint of 74.degree. C.
(Shellsol.RTM. D70) and 40% by weight of high-boiling aromatic
solvent (Solvesso.RTM. 150 ND) having a flashpoint of 65.degree.
C.
[0139] Polymer 2
[0140] Stage 1
[0141] A reactor with stirrer, water separator, jacketed coil
condenser and gas inlet tube is initially charged with 575.8 g of a
C18/C20/C22 mixture of aliphatic linear alcohols (Nafol.RTM. 1822),
2.2 g of p-toluenesulfonic acid, 1.5 g of 4-methoxyphenol and 177.2
g of a high-boiling aliphatic hydrocarbon mixture (Shellsol.RTM.
D70). The water separator is charged with 31 g of Shellsol.RTM.
D70. The reaction mixture is purged with lean air (6% O.sub.2) and
heated to 80.degree. C. while stirring (50 rpm) in order to
dissolve the aliphatic alcohol. After increasing the stirrer speed
to 200 rpm, 135.5 g of acrylic acid are metered in and the
temperature is increased to a maximum of 160.degree. C., such that
water of reaction formed can be distilled off. After 6 h, a further
363.4 g of Shellsol.RTM. D70 are added and the reaction is ended. A
solution of alkyl acrylates having C18/C20/C22 alkyl radicals in
Shellsol.RTM. D70 is obtained (concentration 55% by weight of
acrylates).
[0142] Stage 2
[0143] In a four-neck flask with Teflon stirrer, jacketed coil
condenser and Dosimat, 1224.0 g of the monomer solution (55% by
weight of acrylates) are heated to 75.degree. C. while stirring
(300 rpm) under an N.sub.2 blanket, and 166.1 g of the
abovementioned ethylene-vinyl acetate copolymer are added and
dissolved. Then 8 g of Shellsol.RTM. D70 are added. After adding
20.37 g of allyl alcohol, 2.9 g of the initiator dimethyl
2,2'-azoisobutyrate (Wako V-601) dissolved in 78.4 g of a
high-boiling aliphatic solvent (Shellsol.RTM. D70) are metered in
at an internal temperature of 77-82.degree. C. over 4 hours. After
further polymerization at 78-87.degree. C. for 2.5 hours, the
mixture is diluted with 265.7 g of Solvesso.RTM. 150 ND and cooled
to 40.degree. C., before 1.1 g of triethanolamine are added and the
mixture is stirred for a further 30 min. Finally, the mixture is
filtered through a 400 .mu.m fast sieve.
[0144] A solution is obtained which comprises 49% by weight of
graft copolymers (approx. 20% by weight of ethylene-vinyl acetate
copolymer and approx. 80% by weight of polyacrylate, based in each
case on the graft copolymer), 32% by weight of high-boiling
aliphatic solvent having a flashpoint of 74.degree. C.
(Shellsol.RTM. D70) and 19% by weight of high-boiling aromatic
solvent (Solvesso.RTM. 150 ND) having a flashpoint of 65.degree.
C.
[0145] Further polymer formulations were obtained by varying the
above experimental conditions: [0146] Formulation C1 The procedure
was as in example 1, except that toluene (flashpoint 6+ C.) was
used as the solvent in place of each of the Shellsol.RTM. D70 and
Solvesso.RTM. 150 ND solvents. [0147] Formulation C2 The procedure
was as in example 2, except that toluene (flashpoint 6.degree. C.)
was used as the solvent in place of each of the Shellsol.RTM. D70
and Solvesso.RTM. 150 ND solvents. [0148] Formulation C3 The
procedure was as in example 1, except that exclusively the
Solvesso.RTM. 150 ND solvent was used. [0149] Formulation C4 The
procedure was as in example 2, except that exclusively the
Solvesso.RTM. 150 ND solvent was used. [0150] Formulation C5 The
procedure was as in example 1, except that exclusively the
Solvesso.RTM. 150 ND solvent was used. In addition, the
concentration of The acrylates during the polymerization was
increased (use of a solution with 80% by weigh of monomers rather
than 50% by weight of monomers as in example 1 and in C6).
Concentration of the graft copolymer solution obtained: 49.4% by
weight. [0151] Formulation C6 The procedure was as in example 2,
except that exclusively the Solvesso.RTM. 150 ND solvent was used.
In addition, the concentration of the acrylates during the
polymerization was increased (use of a solution with 79% by weight
of monomers rather than 37% by weight of monomers). Concentration
of the graft copolymer solution obtained: 49.4% by weight. [0152]
Formuation C7 The procedure was as in example 1, except that the
solvent used was exclusively the Shellsol.RTM. D70. [0153]
Formulation C8 The procedure was as in example 2, except that the
solvent used was exclusively the Shellsol.RTM. D70.
[0154] B Test of the Properties of the Copolymer Formulations
Obtained
[0155] The solutions of the copolymers obtained were used to
conduct each of the following tests:
[0156] Determination of the K Values of the Copolymers
[0157] The K values of the copolymers obtained (measured according
to H. Fikentscher, Cellulosechemie, volume 13, pages 58 to 64 and
71 to 74 (1932)) were determined in 2% (wt./vol.) toluenic
solution. The values are compiled in tables 1 to 3.
[0158] Molecular Weight Determination
[0159] The number-average molecular weight M.sub.n and the
weight-average molecular weight M.sub.w of each of the copolymers
obtained were determined by means of gel permeation chromatography
in tetrahydrofuran as the solvent. The values are compiled in
tables 1 to 3.
[0160] Determination of Viscosity:
[0161] The kinematic viscosity of each of the solutions of the
graft copolymers obtained in the experiments described above was
measured with an Ubbelohde viscometer at 50.degree. C. The values
are compiled in tables 1 to 3.
[0162] Assessment of Stability
[0163] The stability of each polymer solution was examined,
specifically with respect to whether a solution which has prolonged
stability and does not have a tendency to phase separation is
maintained. For this purpose, the formulations produced, after
synthesis, were stored at room temperature. If noticeable phase
separation occurs within 24 h after commencement of storage, the
assessment is negative (-), otherwise (+). The values are compiled
in tables 1 to 3.
[0164] Determination of the Pour Point
[0165] The determination of the pour point was conducted to ASTM D
5853 "Standard Test Method for Pour Point of Crude Oils". The pour
point is the minimum temperature at which a sample of a tested oil
is still just free-flowing. According to ASTM D 5853, for this
purpose, a sample of the oil is cooled in steps of 3.degree. C.
each and the flowability is tested after each step. For the tests,
a crude oil from the "Landau" oilfield in south-west Germany
(Wintershall Holding GmbH) having an API gravity of 37 and a pour
point of 27.degree. C. was used. To determine the lowering of the
pour point, the graft copolymers to be tested were used to the oil
in a concentration of 100 ppm, 300 ppm or 1500 ppm, in each case of
polymer based on the crude oil. The values are compiled in tables 1
to 3. Double or triple determinations were conducted on some
samples. In these cases, all values are reported in the table.
TABLE-US-00002 TABLE 1 Inventive examples Pour point [.degree. C.]
Viscosity M.sub.n Stability of Amount of the additives Formulation
at 50.degree. C. M.sub.w the solution 100 300 1500 No. Acrylates
[mm.sup.2/s] [g/mol] M.sub.w/M.sub.n K value at RT ppm ppm ppm
Comments 1 C16/C18 305 2450 29.3 38.8 + 3/6/6 3/0/3 6/9/9 Use of
aliphatic hydrocarbons S1 71900 cloudy, and aromatic hydrocarbons
S2 with stable and flashpoint > 60.degree. C. liquid 2
C18/C20/C22 151 2230 25.6 34.8 + 6/6/9 3/0/3 9/6/6 Use of aliphatic
hydrocarbons S1 57000 stable and and aromatic hydrocarbons S2 with
solid flashpoint > 60.degree. C.
TABLE-US-00003 TABLE 2 Comparative examples Pour point [.degree.
C.] Formu- Viscosity M.sub.n Stability of Amount of the additives
lation at 50.degree. C. M.sub.w the solution 100 300 1500 No.
Acrylates [mm.sup.2/s] [g/mol] M.sub.w/M.sub.n K value at RT ppm
ppm ppm Comments C1 C16/C18 253 4610 16.1 40.4 + 9/9 6/6 9/9*
toluene as solvent, flashpoint 6.degree. C. 74400 cloudy, liquid C2
C18/C20/C22 148 3680 16.3 36.3 + 12/9 6/9 9/9* toluene as solvent,
flashpoint 6.degree. C. 60000 cloudy, solid C3 C16/C18 70 1620 24.3
35.6 - n.d. n.d. n.d. Only aromatic hydrocarbons S2 with 39400
inhomogeneous flashpoint > 60.degree. C., much lower molecular
weight, inadequate stability C4 C18/C20/C22 73 1680 25.4 32.4 -
12/15 9/9 3/6 Only aromatic hydrocarbons S2 with 42700 waxy, solid
flashpoint > 60.degree. C., much lower molecular weight,
formulation is solid C5 C16/C18 156 1570 22.4 34.4 - n.d. n.d. n.d.
Polymerization in higher concentration 35200 biphasic Only aromatic
hydrocarbons S2 with flashpoint > 60.degree. C., much lower
molecular weight, inadequate stability C6 C18/C20/C22 162 2040 27.5
34.1 - 6/9 6/9 18/15 Polymerization in higher concentration 56200
cloudy, waxy Only aromatic hydrocarbons S2 with solid flashpoint
> 60.degree. C., formulation is solid *measured at 1000 ppm
TABLE-US-00004 TABLE 3 Comparative examples (continued) Pour point
[.degree. C.] Viscosity M.sub.n Stability of Amount of the
additives Formulation at 50.degree. C. M.sup.w the solution 100 300
1500 No. Acrylates [mm.sup.2/s] [g/mol] M.sub.w/M.sub.n K value at
RT ppm ppm ppm Comments C7 C16/C18 184 2630 25.3 40 - n.d. n.d.
n.d. Only aliphatic hydrocarbons S1 with 66600 solid flashpoint
> 60.degree. C., solid product C8 C18/C20/C22 120 1380 34.8 33.4
- 12/12 6/6 6/6 Only aliphatic hydrocarbons S1 with 48100 waxy,
solid flashpoint > 60.degree. C., solid product
[0166] The examples and comparative examples show the advantages of
the process according to the invention. C1 (with C16/C18 acrylates)
and C2 (with C18/C20/C22 acrylates) are products according to the
prior art which have been prepared in toluene (flashpoint 6.degree.
C.). The product with C.sub.16/18 acrylates is liquid, and both
products are stable. The pour point of the test oil (27.degree. C.)
is reduced to 6 to 9.degree. C. by formulation C1 according to the
amount, and to 6 to 9.degree. C. by formulation C2.
[0167] The formulations 1 (with C16/C18 acrylates) and 2 (with
C18/C20/C22 acrylates) which have been obtained by means of the
process according to the invention and have been prepared using
solvents S1 and S2 are likewise stable and actually lead to
somewhat lower pour points in the test (0.degree. C. to 9.degree.
C. in each case). What is surprising is the concentration
dependence of the reduction in the pour point, the experiments
showing a minimum of only 0.degree. C. to 3.degree. C. at 300 ppm
both for C1 and for C2, while 3.degree. C. to 6.degree. C. are
measured at 100 ppm and 6.degree. C. to 9.degree. C. at 1500 ppm
for C1, and 6 to 9.degree. C. both at 100 ppm and at 1500 ppm for
C2.
[0168] If toluene as the solvent (boiling point 111.degree. C.,
flashpoint 6.degree. C.) is replaced exclusively by aromatic
solvents having a flashpoint >60.degree. C. (C3, C4, C5, C6),
this choice of solvent distinctly influences the course of the
polymerization. Both the number-average molecular weight M.sub.n
and the weight-average molecular weight M.sub.w of the polymers
increase compared to the corresponding experiments in toluene, and
the polydispersity increases. The resulting formulations no longer
have adequate stability and are either biphasic or waxy solids.
Moreover, the lowering of the pour point is no longer as good in
all concentration ranges as the products in toluene.
[0169] If toluene as the solvent is replaced exclusively by
aliphatic solvents having a flashpoint >60.degree. C. (C7, C8),
solid or waxy solid products are obtained, which have to be melted
for use. The lowering of the pour point is smaller than in the case
of the inventive experiments with a mixture of solvents (S1) and
(S2).
* * * * *