U.S. patent application number 13/515376 was filed with the patent office on 2013-01-03 for multifunctional cooling additives for middle distillates, having an improved flow capability.
This patent application is currently assigned to CLARIANT FINANCE (BVI) LIMITED. Invention is credited to Stefan Dilsky, Sabine Goetzke, Matthias Krull, Dirk Leinweber, Werner Reimann.
Application Number | 20130000184 13/515376 |
Document ID | / |
Family ID | 43928932 |
Filed Date | 2013-01-03 |
United States Patent
Application |
20130000184 |
Kind Code |
A1 |
Krull; Matthias ; et
al. |
January 3, 2013 |
Multifunctional Cooling Additives For Middle Distillates, Having An
Improved Flow Capability
Abstract
The present invention relates to cooling additives for middle
distillates, containing A) at least one comb polymer carrying
hydroxyl groups, which can be produced by polycondensation of a
polyol that contains two primary OH groups and at least one
secondary OH group with a dicarboxylic acid or the anhydride or
ester thereof, which carries a C.sub.16-C.sub.40 alkyl radical or a
C.sub.16-C.sub.40 alkenyl radical, characterized in that the OH
number of the comb polymer is at least 40 mg KOH/g, B) at least one
copolymer of ethylene and of at least one ethylenically unsaturated
ester, and C) at least one organic solvent.
Inventors: |
Krull; Matthias; (Harxheim,
DE) ; Reimann; Werner; (Frankfurt, DE) ;
Dilsky; Stefan; (Gerbrunn, DE) ; Goetzke; Sabine;
(Liederbach, DE) ; Leinweber; Dirk; (Kelkheim,
DE) |
Assignee: |
CLARIANT FINANCE (BVI)
LIMITED
Tortola
VG
|
Family ID: |
43928932 |
Appl. No.: |
13/515376 |
Filed: |
December 7, 2010 |
PCT Filed: |
December 7, 2010 |
PCT NO: |
PCT/EP2010/007407 |
371 Date: |
June 12, 2012 |
Current U.S.
Class: |
44/404 ; 508/463;
508/506 |
Current CPC
Class: |
C10L 10/16 20130101;
C10L 1/143 20130101; C10L 1/1608 20130101; C10L 1/1985 20130101;
C10L 1/1963 20130101; C10L 1/1641 20130101; C10L 1/1616 20130101;
C10L 10/14 20130101; C10L 1/224 20130101; C10L 1/1973 20130101;
C10L 1/1981 20130101; C10L 1/1983 20130101 |
Class at
Publication: |
44/404 ; 508/506;
508/463 |
International
Class: |
C10L 1/188 20060101
C10L001/188; C10M 169/04 20060101 C10M169/04 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 24, 2009 |
DE |
10 2009 060 371.9 |
Claims
1. A cold additive for middle distillates comprising A) at least
one comb polymer which has hydroxyl groups and wherein the comb
polymer can be prepared by polycondensation of a polyol containing
two primary OH groups and at least one secondary OH group, with a
dicarboxylic acid, or the anhydride thereof or ester thereof,
having a C.sub.16- to C.sub.40-alkyl radical or a C.sub.16- to
C.sub.40-alkenyl radical, wherein the OH number of the comb polymer
is at least 40 mg KOH/g, B) at least one copolymer of ethylene and
at least one ethylenically unsaturated ester, and C) at least one
organic solvent.
2. The cold additive as claimed in claim 1, in which the
dicarboxylic acid is according to the formula 1 ##STR00005##
wherein one of the R.sup.1 to R.sup.4 radicals is a linear
C.sub.16-C.sub.40-alkyl or alkenyl radical and the rest of the
R.sup.1 to R.sup.4 radicals are each independently hydrogen or an
alkyl radical having 1 to 3 carbon atoms, and R.sup.5 is a C--C
bond or an alkylene radical having 1 to 6 carbon atoms.
3. The cold additive as claimed in claim 2, in which the
dicarboxylic acid is alkylsuccinic acid, alkenylsuccinic acid or
the anhydride thereof.
4. The cold additive as claimed in claim 1, wherein the polyol is
glycerol.
5. The cold additive as claimed in claim 1, wherein the at least
one comb polymer A) has an OH number between 40 and 500 mg
KOH/g.
6. The cold additive as claimed in claim 1, wherein the at least
one copolymer B) is a copolymer of ethylene and 8 to 21 mol % of at
least one olefinically unsaturated compound selected from the group
consisting of vinyl esters, acrylic esters and methacrylic
esters.
7. The cold additive as claimed in claim 1, wherein the at least
one solvent C) is selected from the group consisting of aliphatic
hydrocarbons having 9 to 20 carbon atoms and aromatic hydrocarbons
having 7 to 20 carbon atoms.
8. The cold additive as claimed in claim 1, wherein the at least
one solvent C) additionally comprises a solubilizer which contains
4 to 24 carbon atoms and is selected from the group consisting of
alcohols, organic acids, ethers of organic acids, esters of organic
acids, and mixtures thereof.
9. The cold additive as claimed in claim 1, comprising 0.1 to 50%
by weight of A), 1.5 to 73.5% by weight of B) and 25 to 95% by
weight of C).
10. The cold additive as claimed in claim 1, further comprising at
least one further cold flow improver, selected from the group
consisting of III) oil-soluble polar nitrogen compounds, IV) resins
of phenol derivatives bearing alkyl radicals with aldehydes, V)
comb polymers of the formula ##STR00006## in which A is R', COOR',
OCOR', R''--COOR', OR'; D is H, CH.sub.3, A or R''; E is H, A; G is
H, R'', R''--COOR', an aryl radical or a heterocyclic radical; M is
H, COOR'', OCOR'', OR'', COOH; N is H, R'', COOR'', OCOR, an aryl
radical; R' is a hydrocarbyl chain having 8 to 50 carbon atoms; R''
is a hydrocarbyl chain having 1 to 10 carbon atoms; a is a number
between 0.4 and 1.0; and b is a number between 0 and 0.6, VI) homo-
and copolymers of olefins having 2 to 30 carbon atoms, and VII)
esters, ethers and ester/ethers of alkoxylated polyols, which have
at least one alkyl radical having 12 to 30 carbon atoms.
11. A process for improving the cold flow properties of fuel oils,
comprising the step of adding a cold additive as claimed in claim 1
to a middle distillate.
12. A fuel oil comprising a middle distillate and at least one cold
additive as claimed in claim 1.
13. The fuel oil as claimed in claim 12, in which the middle
distillate has a content of constituents having an n-alkyl chain
having 16 or more carbon atoms of more than 4% by weight.
14. The fuel oil as claimed in claim 12, in which the middle
distillate has a proportion of long-chain n-paraffins having 28 or
more carbon atoms of less than 1% by weight.
Description
[0001] The present invention relates to cold additives for middle
distillates which have improved manageability at low temperatures,
and to the use thereof for improvement of cold properties and
lubricity of middle distillates, and to the corresponding middle
distillates.
[0002] In view of decreasing global oil reserves, ever heavier and
hence paraffin-richer crude oils are being extracted and processed,
which consequently also lead to paraffin-richer fuel oils. The
paraffins present in crude oils and middle distillates in
particular, such as gas oil, diesel and heating oil, can
crystallize out as the temperature of the oil is lowered and
agglomerate with intercalation of oil. This crystallization and
agglomeration can result, in winter in particular, in blockages of
the filters in engines and boilers, which prevent reliable dosage
of the fuels and, under some circumstances, can cause complete
interruption of the motor fuel or boiler fuel supply. Typically,
even 0.1 to 0.3% by weight of crystallized paraffins in the oil are
sufficient to block the fuel filter. The paraffin problem is
additionally aggravated by the hydrogenating desulfurization of
fuel oils, which has to be undertaken for environmental protection
reasons for the purpose of lowering the sulfur content, and leads
to an increased proportion of cold-critical paraffins and to a
reduced proportion of mono- and polycyclic aromatics, which improve
the solubility of paraffins, in the fuel oil.
[0003] The cold flow properties of middle distillates are often
improved by adding chemical additives known as cold flow improvers
or flow improvers, which modify the crystal structure and
agglomeration tendency of the paraffins which precipitate out such
that the oils thus additized can still be pumped and used at
temperatures which are often more than 20.degree. C. lower than in
the case of unadditized oils. The cold flow improvers used are
typically oil-soluble copolymers of ethylene and unsaturated
esters.
[0004] For example, according to DE-A-11 47 799 oil-soluble
copolymers of ethylene and vinyl acetate having a molecular weight
between about 1000 and 3000 are added to mineral oil distillate
fuels having a boiling range between about 120 and 400.degree. C.
Preference is given to copolymers containing about 60 to 99% by
weight of ethylene and about 1 to 40% by weight of vinyl
acetate.
[0005] For the additization of middle distillates having a high
content of longer-chain paraffins in particular, these copolymers
of ethylene and unsaturated esters are often used together with
comb polymers. Comb polymers are understood to mean a specific form
of the branched macromolecules, which bear comparatively long alkyl
side chains of more or less equal length at more or less regular
intervals on a linear main chain. Often, in the case of combined
use of copolymers of ethylene and unsaturated esters with comb
polymers, synergistically enhanced efficacies as cold additives are
reported, and these are probably based on a nucleating function of
these comb polymers on paraffin crystallization. These occur
especially in the case of use of comb polymers with very long side
chains.
[0006] U.S. Pat. No. 3,447,916 discloses condensation polymers
formed from alkenylsuccinic anhydrides, polyols and fatty acids for
lowering of the pour point of hydrocarbon oils. In these polymers,
the hydroxyl groups of the polyol have been very substantially
esterified. The document does not give any indications of combined
use with further additives.
[0007] DE-A-19 20 849 discloses condensation polymers of
alkenylsuccinic anhydrides, polyols having at least 4 OH groups and
fatty acids for lowering of the pour point of hydrocarbon oils. The
stoichiometry of the reactants used for the condensation is
preferably selected such that the number of moles of OH groups and
carboxyl groups is the same, i.e. there is essentially complete
esterification. As a result of the use of polyhydric alcohols,
these polymers, according to the information in the disclosure,
have an efficacy superior to the additives of U.S. Pat. No.
3,447,916. This document does not give any indications of combined
use with further additives either.
[0008] DE-A-24 51 047 discloses light, low-viscosity distillate
fuel oils which do not comprise any residues and have been
additized with ethylene copolymers and comb polymers having
C.sub.18-C.sub.44 side chains. The comb polymers used include
polyesters of alk(en)ylsuccinic anhydride with a
C.sub.16-C.sub.44-alk(en)yl radical, a polyol having 2-6 OH groups
and a C.sub.20-C.sub.44-monocarboxylic acid. The three components
of the polyester are preferably condensed in equimolar amounts, so
as to result in essentially complete esterification of OH and also
COOH groups. Demonstrated by way of example (polymer G) is a
polycondensate of equimolar amounts of C.sub.22-28-alkenylsuccinic
anhydride, trimethylolpropane and C.sub.20-22 fatty acids.
[0009] US-A-2008/0295397 discloses additives for lowering the pour
point of diesel oils, which comprise polyglyceryl esters and
optionally further pour point depressants, for example
ethylene/vinyl ester copolymers. The hydroxyl groups of the
polyglycerol may be fully or partially esterified. Such polyol
partial esters have pronounced emulsification properties and are
therefore undesirable in fuels.
[0010] Additive combinations of copolymers of ethylene and
unsaturated esters and comb polymers, said combinations being used
for the improvement of the cold properties of middle distillates,
are typically used as concentrates in organic solvents in order to
improve the manageability thereof. In this context, it is important
particularly for the use of such additive concentrates at isolated
sites, where there is often no means of heating the additive
concentrates, that they remain free-flowing and miscible into fuel
oils which are likewise cold at minimum temperature. At the same
time, however, the active ingredient concentration in the
concentrates should be at a maximum in order to minimize the volume
of the additive concentrates to be transported and stored.
[0011] The prior art comb polymers prepared by polycondensation
exhibit, as concentrates in organic solvents, and also in a blend
with copolymers of ethylene and unsaturated esters in organic
solvents, often comparatively high intrinsic pour points of more
than 20.degree. C. in some cases. At filling stations, and also in
isolated areas, for example in the mountains or in Arctic regions,
however, heated storage of the additive concentrates is often
impossible. Dilution of the additives is undesirable for logistical
reasons since the volumes to be transported and stored then
increase significantly.
[0012] Consequently, there is a need for highly effective cold
additives for middle distillates, said cold additives being highly
active and also manageable without problem at low ambient
temperatures, and improving the cold flow properties of the middle
distillates with minimum dosages. These additives shall also be
free-flowing at low temperatures and be readily soluble in the
middle distillate to be additized. In addition, they shall not
impair the filterability of the additized middle distillates, or at
least do so to a minimum degree. Furthermore, they shall improve
lubricity, especially in reduced-sulfur or sulfur-free middle
distillates.
[0013] It has been found that, surprisingly, additive combinations
which comprise solutions of copolymers of ethylene and unsaturated
esters, and specific polycondensates of dicarboxylic acids or
dicarboxylic anhydrides bearing linear C.sub.16-C.sub.40-alkyl
radicals or C.sub.16-C.sub.40-alkenyl radicals, and polyols having
two primary and at least one secondary OH group, in organic
solvents are free-flowing in concentrated form and have good
solubility in middle distillates even at low temperatures of below
10.degree. C., often below 0.degree. C., in some cases below
-10.degree. C., for example below -20.degree. C. In addition, they
have excellent properties as cold flow improvers without impairing
the filterability of the oils additized therewith. In the synthesis
of these polycondensates, in spite of dispensing with the fatty
acids typically used in addition for the esterification in the
prior art, there is surprisingly no formation or formation only to
a degree insignificant for use, of crosslinked high molecular
weight structures which lead to impairment of filterability in the
additized oil. Furthermore, these additive combinations are capable
of improving the lubricant properties of low-sulfur oils.
[0014] The invention provides cold additives for middle distillates
comprising [0015] A) at least one comb polymer which bears hydroxyl
groups and can be prepared by polycondensation of a polyol
containing two primary OH groups and at least one secondary OH
group, with a dicarboxylic acid, or the anhydride thereof or ester
thereof, bearing a C.sub.16- to C.sub.40-alkyl radical or a
C.sub.16- to C.sub.40-alkenyl radical, the OH number of said comb
polymer being at least 40 mg KOH/g, [0016] B) at least one
copolymer of ethylene and at least one ethylenically unsaturated
ester, and [0017] C) at least one organic solvent.
[0018] The invention further provides a process for improving the
cold flow properties of fuel oils, by adding to a middle distillate
an additive which comprises [0019] A) at least one comb polymer
which bears hydroxyl groups and can be prepared by polycondensation
of a polyol containing two primary OH groups and at least one
secondary OH group, with a dicarboxylic acid, or the anhydride
thereof or ester thereof, bearing a C.sub.16- to C.sub.40-alkyl
radical or a C.sub.16- to C.sub.40-alkenyl radical, the OH number
of said polymer being at least 40 mg KOH/g, [0020] B) at least one
copolymer of ethylene and at least one ethylenically unsaturated
ester, and [0021] C) at least one organic solvent.
[0022] The invention further provides a process for improving the
lubricity of fuel oils, by adding to a middle distillate having a
sulfur content of less than 0.05% by weight an additive which
comprises [0023] A) at least one comb polymer which bears hydroxyl
groups and can be prepared by polycondensation of a polyol
containing two primary OH groups and at least one secondary OH
group, with a dicarboxylic acid, or the anhydride thereof or ester
thereof, bearing a C.sub.16- to C.sub.40-alkyl radical or a
C.sub.16- to C.sub.40-alkenyl radical, the OH number of said
polymer being at least 40 mg KOH/g, [0024] B) at least one
copolymer of ethylene and at least one ethylenically unsaturated
ester, and [0025] C) at least one organic solvent.
[0026] The invention further provides fuel oils comprising a middle
distillate and a cold additive which comprises [0027] A) at least
one polyester comb polymer which bears hydroxyl groups and can be
prepared by polycondensation of a polyol containing two primary OH
groups and at least one secondary OH group, with a dicarboxylic
acid, or the anhydride thereof or ester thereof, bearing a
C.sub.16- to C.sub.40-alkyl radical or a C.sub.16- to
C.sub.40-alkenyl radical, the OH number of said polymer being at
least 40 mg KOH/g, [0028] B) at least one copolymer of ethylene and
at least one ethylenically unsaturated ester, and [0029] C) at
least one organic solvent.
[0030] The comb polymer A bearing hydroxyl groups is generally
obtained by the polycondensation of a dicarboxylic acid bearing a
C.sub.16- to C.sub.40-alkyl radical or -alkenyl radical, also
referred to collectively hereinafter as C.sub.16-C.sub.40-alk(en)yl
radical, with the primary hydroxyl groups of the polyol. It is
preferable that the secondary OH groups remain essentially
unesterified. The preferred structure of the comb polymer A bearing
hydroxyl groups can thus be illustrated, for example, in accordance
with formula A1:
##STR00001## [0031] in which [0032] one of the R.sup.1 to R.sup.4
radicals is a linear C.sub.16-C.sub.40-alkyl or -alkenyl radical
and the rest of the R.sup.1 to R.sup.4 radicals are each
independently hydrogen or an alkyl radical having 1 to 3 carbon
atoms, [0033] R.sup.5 is a C--C bond or an alkylene radical having
1 to 6 carbon atoms, [0034] R.sup.16 is a hydrocarbyl group bearing
at least one hydroxyl group and having 3 to 10 carbon atoms, [0035]
n is a number from 1 to 100, [0036] m is a number from 3 to 250,
[0037] p is 0 or 1, and [0038] q is 0 or 1.
[0039] Preferred dicarboxylic acids which bear
C.sub.16-C.sub.40-alkyl- and/or alkenyl radicals and are suitable
for preparation of the comb polymers A) bearing hydroxyl groups
correspond to the general formula 1
##STR00002##
in which one of the R.sup.1 to R.sup.4 radicals is a linear
C.sub.16-C.sub.40-alkyl or -alkenyl radical and the other R.sup.1
to R.sup.4 radicals are each independently hydrogen or an alkyl
radical having 1 to 3 carbon atoms and R.sup.5 is a C--C bond or an
alkylene radical having 1 to 6 carbon atoms.
[0040] More preferably, one of the R.sup.1 to R.sup.4 radicals is a
linear C.sub.16-C.sub.40-alkyl or -alkenyl radical, one is a methyl
group and the rest are hydrogen. In a specific embodiment, one of
the R.sup.1 to R.sup.4 radicals is a linear C.sub.16-C.sub.40-alkyl
or -alkenyl radical and the others are hydrogen. In a particularly
preferred embodiment, R.sup.5 is a C--C single bond. More
particularly, one of the R.sup.1 to R.sup.4 radicals is a linear
C.sub.16-C.sub.40-alkyl or -alkenyl radical, the other R.sup.1 to
R.sup.4 radicals are hydrogen and R.sup.5 is a C--C single
bond.
[0041] The dicarboxylic acids or anhydrides thereof bearing alkyl
and/or alkenyl radicals can be prepared by known processes. For
example, they can be prepared by heating ethylenically unsaturated
dicarboxylic acids with olefins ("ene reaction") or with
chloroalkanes. Preference is given to the thermal addition of
olefins onto ethylenically unsaturated dicarboxylic acids, which is
typically performed at temperatures between 100 and 250.degree. C.
The dicarboxylic acids and dicarboxylic anhydrides bearing alkenyl
radicals formed can be hydrogenated to dicarboxylic acids and
dicarboxylic anhydrides bearing alkyl radicals. Dicarboxylic acids
and anhydrides thereof preferred for the reaction with olefins are
maleic acid and more preferably maleic anhydride. Additionally
suitable are itaconic acid, citraconic acid and the anhydrides
thereof, and the esters of the aforementioned acids, especially
those with lower C.sub.1-C.sub.8-alcohols, for example methanol,
ethanol, propanol and butanol.
[0042] For the preparation of the dicarboxylic acids or anhydrides
thereof bearing alkyl radicals, preference is given to using linear
olefins having 16 to 40 carbon atoms and especially having 18 to 36
carbon atoms, for example having 19 to 32 carbon atoms. In a
particularly preferred embodiment, mixtures of olefins with
different chain lengths are used. Preference is given to using
mixtures of olefins and especially of .alpha.-olefins having 18 to
36 carbon atoms, for example mixtures in the C.sub.20-C.sub.22,
C.sub.20-C.sub.24, C.sub.24-C.sub.28, C.sub.26-C.sub.28,
C.sub.30-C.sub.36 range. These olefins may also contain minor
amounts of shorter- and/or longer-chain olefins, but preferably not
more than 10% by weight and especially not more than 0.1 to 5% by
weight. Preferred olefins have a linear or at least substantially
linear alkyl chain. "Linear or substantially linear" is understood
to mean that at least 50% by weight, preferably 70 to 99% by
weight, especially 75 to 95% by weight, for example 80 to 90% by
weight, of the olefins have a linear component having 16 to 40
carbon atoms. Suitable olefins are preferably technical alkene
mixtures. These contain preferably at least 50% by weight, more
preferably 60 to 99% by weight and especially 70 to 95% by weight,
for example 75 to 90% by weight, of terminal double bonds
(.alpha.-olefins). In addition, they may contain up to 50% by
weight, preferably 1 to 40% by weight and especially 5 to 30% by
weight, for example 10 to 25% by weight, of olefins having an
internal double bond, for example having vinylidene double bonds
with the structural element R.sup.17--CH.dbd.C(CH.sub.3).sub.2,
where R.sup.17 is an alkyl radical having 12 to 36 carbon atoms and
especially having 14 to 32 carbon atoms, for example having 15 to
28 carbon atoms. In addition, minor amounts of secondary components
of technical origin, for example paraffins, may be present, but
preferably not more than 5% by weight. Particular preference is
given to olefin mixtures containing at least 75% by weight of
linear .alpha.-olefins having a carbon chain length in the range
from C.sub.20 to C.sub.24.
[0043] Preferred comb polymers A) bearing hydroxyl groups are
preparable by reaction of alkyl- or alkenylsuccinic acids bearing a
linear C.sub.16-C.sub.40-alkyl or -alkenyl radical and/or
anhydrides thereof with polyols which bear two primary and at least
one secondary hydroxyl group.
[0044] Preferred polyols are glycerol, poly(glycerol) and mixtures
thereof. Poly(glycerol) is understood to mean especially structures
derivable from glycerol by polycondensation. The degree of
condensation of poly(glycerols) preferred in accordance with the
invention is between 2 and 50, more preferably between 3 and 25 and
especially between 4 and 20, for example between 5 and 15. The
preparation of poly(glycerol) is known in the prior art. It can be
effected, for example, via addition of 2,3-epoxy-1-propanol
(glycide) onto glycerol. In addition, the preparation of
poly(glycerol) can be effected by polycondensation of glycerol,
which is known per se. The reaction temperature in the
polycondensation is generally between 150 and 300.degree. C.,
preferably between 200 and 250.degree. C. The polycondensation is
normally performed at atmospheric pressure. Examples of catalyzing
acids include HCl, H.sub.2SO.sub.4, organic sulfonic acids or
H.sub.3PO.sub.4, and examples of catalyzing bases NaOH or KOH. The
catalysts are added to the reaction mixture preferably in amounts
of 0.01 to 10% by weight, more preferably 0.1 to 5% by weight,
based on the weight of the reaction mixture. The polycondensation
can be performed in a solvent-free manner or else in the presence
of solvents. If the polycondensation is effected in the presence of
solvents, the proportion thereof in the reaction mixture is
preferably 0.1 to 70% by weight, for example 10 to 60% by weight.
Preferred solvents are the solvents which are also used as
component C) for the additive mixture. The polycondensation
generally takes 3 to 10 hours.
[0045] The reaction of the dicarboxylic acids bearing alkyl
radicals, the anhydrides thereof or esters thereof with the polyol
is effected preferably in a molar ratio of 1:2 to 2:1, more
preferably in a molar ratio of 1:1.5 to 1.5:1, and especially in a
molar ratio of 1:1.2 to 1.2:1, for example an equimolar ratio.
Particular preference is given to effecting the reaction with an
excess of polyol. Particularly useful molar excesses have been
found to be from 1 to 10 mol % and especially 1.5 to 5 mol %, based
on the amount of dicarboxylic acid used. The condensation is
effected preferably by heating C.sub.16-C.sub.40-alkyl or
-alkenyl-substituted dicarboxylic acid or the anhydride or ester
thereof with the polyol to temperatures above 100.degree. C. and
preferably to temperatures between 120 and 320.degree. C., for
example to temperatures between 150 and 290.degree. C. To establish
the molecular weight of the comb polymers A), which is important
for the efficacy, it is typically necessary to remove water or
alcohol of reaction, which can be effected, for example, by
distillative removal. Azeotropic removal by means of suitable
organic solvents is also suitable for this purpose. To accelerate
the polycondensation, it has often been found to be useful to add
catalysts to the reaction mixture. Suitable catalysts are known
acidic, basic and organometallic compounds.
[0046] In a preferred embodiment, to establish the molecular
weight, minor amounts of the dicarboxylic acids bearing alk(en)yl
radicals, anhydrides thereof or esters thereof are replaced in the
reaction mixture by C.sub.1- to C.sub.18-monocarboxylic acids,
preferably C.sub.2- to C.sub.16-monocarboxylic acids and especially
C.sub.3- to C.sub.14-monocarboxylic acids, for example C.sub.4- to
C.sub.12-monocarboxylic acids. However, not more than 20 mol % and
preferably 0.1 to 10 mol %, for example 0.5 to 5 mol %, of the
dicarboxylic acids bearing alk(en)yl radicals, anhydrides thereof
or esters thereof is replaced by one or more monocarboxylic acids.
In addition, it is also possible to replace minor amounts, for
example up to 10 mol % and especially 0.01 to 5 mol % of the
alk(en)yl-succinic acids or anhydrides thereof, with further
dicarboxylic acids, for example succinic acid, glutaric acid,
maleic acid and/or fumaric acid. More preferably, the comb polymers
A) bearing hydroxyl groups are prepared in the absence of
monocarboxylic acids.
[0047] In a further preferred embodiment, to establish the
molecular weight, minor amounts of the polyol in the reaction
mixture are replaced by C.sub.1- to C.sub.30-monoalcohols,
preferably C.sub.2- to C.sub.24-monoalcohols and especially
C.sub.3- to C.sub.18-monoalcohols, for example C.sub.4- to
C.sub.12-monoalcohols. Preferably at most 20 mol % and more
preferably 0.1 to 10 mol %, for example 0.5 to 5 mol %, of the
polyol is replaced by one or more monoalcohols. More preferably,
the comb polymers A) bearing hydroxyl groups are prepared in the
absence of monoalcohols. In addition, the polyol bearing two
primary hydroxyl groups and at least one secondary hydroxyl group
may also be replaced in minor amounts of up to 10 mol %, for
example 0.01 to 5 mol %, by one or more diols. Preference is given
to diols such as ethylene glycol, propylene glycol and/or neopentyl
glycol, for example. More preferably, the comb polymers A) bearing
hydroxyl groups are prepared in the absence of diols.
[0048] The mean degree of condensation of the inventive comb
polymers A) bearing hydroxyl groups is preferably between 4 and
200, more preferably between 5 and 150 and especially between 7 and
100, for example between 10 and 50 repeat units of dicarboxylic
acid and polyol. The weight-average molecular weight Mw of the comb
polymers A) bearing hydroxyl groups, determined in THF by means of
GPC against poly(ethylene glycol) standards, is preferably between
1500 and 100 000 g/mol and especially between 2500 and 50 000
g/mol, for example between 4000 and 20 000 g/mol.
[0049] The acid number of the comb polymers A) bearing hydroxyl
groups is preferably less than 40 mg KOH/g and more preferably less
than 30 mg KOH/g, for example less than 20 mg KOH/g. The acid
number can be determined, for example, by titration of the polymer
with alcoholic tetra-n-butylammonium hydroxide solution in
xylene/isopropanol. Additionally preferably, the hydroxyl number of
the comb polymers A) is between 45 and 500 mg KOH/g, more
preferably between 50 and 300 mg KOH/g and especially between 60
and 250 mg KOH/g. The hydroxyl number can be determined, after
reaction of the free OH groups with isocyanate, by means of .sup.1H
NMR spectroscopy by quantitative determination of the urethane
formed.
[0050] Preferred copolymers of ethylene and olefinically
unsaturated esters B) are especially those which, as well as
ethylene, contain 8 to 21 mol % and especially 10 to 19 mol % of
olefinically unsaturated esters as comonomers.
[0051] The olefinically unsaturated esters are preferably vinyl
esters, acrylic esters and/or methacrylic esters. It is possible
for one or more esters to be present as comonomers in the
polymer.
[0052] The vinyl esters are preferably those of the formula 2
CH.sub.2.dbd.CH--OCOR.sup.12 (2)
in which R.sup.12 is C.sub.1- to C.sub.30-alkyl, preferably
C.sub.1- to C.sub.16-alkyl, especially C.sub.1- to C.sub.12-alkyl.
In a further embodiment, the alkyl groups mentioned may be
substituted by one or more hydroxyl groups.
[0053] Particularly preferred vinyl esters derive from secondary
and especially tertiary carboxylic acids whose branch is in the
alpha-position to the carbonyl group. Preferably, R.sup.12 in these
vinyl esters is C.sub.4- to C.sub.16-alkyl and especially C.sub.6-
to C.sub.12-alkyl. In a further preferred embodiment, R.sup.12 is a
branched alkyl radical or a neoalkyl radical having 7 to 11 carbon
atoms, especially having 8, 9 or 10 carbon atoms. Suitable vinyl
esters include vinyl acetate, vinyl propionate, vinyl butyrate,
vinyl isobutyrate, vinyl hexanoate, vinyl heptanoate, vinyl
octanoate, vinyl pivalate, vinyl 2-ethylhexanoate, vinyl laurate,
vinyl stearate and Versatic esters such as vinyl neononanoate,
vinyl neodecanoate, vinyl neoundecanoate.
[0054] In a further preferred embodiment, these ethylene copolymers
contain vinyl acetate and at least one further vinyl ester of the
formula 2 in which R.sup.12 is C.sub.4- to C.sub.30-alkyl,
preferably C.sub.4- to C.sub.16-alkyl, especially C.sub.6- to
C.sub.12-alkyl. More preferably, the further vinyl esters are
alpha-branched.
[0055] The acrylic and methacrylic esters, summarized hereinafter
as (meth)acrylic esters, are preferably those of the formula 3
CH.sub.2.dbd.CR.sup.13--COOR.sup.14 (3)
in which R.sup.13 is hydrogen or methyl and R.sup.14 is C.sub.1- to
C.sub.30-alkyl, preferably C.sub.4- to C.sub.16-alkyl, especially
C.sub.6- to C.sub.12-alkyl. Suitable acrylic esters include, for
example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl
(meth)acrylate, n- and isobutyl (meth)acrylate, hexyl, octyl,
2-ethylhexyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl
(meth)acrylate and mixtures of these comonomers. In a further
embodiment, the alkyl groups mentioned may be substituted by one or
more hydroxyl groups. An example of such an acrylic ester is
hydroxyethyl methacrylate.
[0056] The copolymers B) may, as well as olefinically unsaturated
esters, also contain further olefinically unsaturated compounds as
comonomers. Preferred comonomers of this kind are alkyl vinyl
ethers and alkenes.
[0057] The alkyl vinyl ethers are preferably compounds of the
formula 4
CH.sub.2.dbd.CH--OR.sup.15 (4)
in which R.sup.15 is C.sub.1- to C.sub.30-alkyl, preferably
C.sub.4- to C.sub.16-alkyl, especially C.sub.6- to C.sub.12-alkyl.
Examples include methyl vinyl ether, ethyl vinyl ether, isobutyl
vinyl ether. In a further embodiment, the alkyl groups mentioned
may be substituted by one or more hydroxyl groups.
[0058] The alkenes are preferably monounsaturated hydrocarbons
having 3 to 30 carbon atoms, especially 4 to 16 carbon atoms and
especially 5 to 12 carbon atoms. Suitable alkenes include propene,
butene, isobutylene, pentene, hexene, 4-methylpentene, octene,
diisobutylene and norbornene and derivatives thereof such as
methylnorbornene and vinylnorbornene. In a further embodiment, the
alkyl groups mentioned may be substituted by one or more hydroxyl
groups.
[0059] Apart from ethylene, particularly preferred terpolymers
contain 3.5 to 20 mol %, especially 8 to 15 mol %, of vinyl
acetate, and 0.1 to 12 mol %, especially 0.2 to 5 mol %, of at
least one relatively long-chain and preferably branched vinyl
ester, for example vinyl 2-ethylhexanoate, vinyl neononanoate or
vinyl neodecanoate, the total comonomer content of the terpolymers
being preferably between 8.1 and 21 mol %, especially between 8.2
and 19 mol %, for example between 12 and 18 mol %. Further
particularly preferred copolymers contain, in addition to ethylene
and 8 to 18 mol % of vinyl esters of C.sub.2- to
C.sub.12-carboxylic acids, also 0.5 to 10 mol % of olefins such as
propene, butene, isobutylene, hexene, 4-methylpentene, octene,
diisobutylene and/or norbornene, the total comonomer content being
preferably between 8.5 and 21 mol % and especially between 9.0 and
19 mol %.
[0060] These ethylene co- and terpolymers preferably have melt
viscosities at 140.degree. C. of at most 5000 mPas, more preferably
of 20 to 2500 mPas, particularly of 30 to 1000 mPas, especially of
50 to 500 mPas. The degrees of branching determined by means of
.sup.1H NMR spectroscopy are preferably between 1 and 9
CH.sub.3/100 CH.sub.2 groups, especially between 2 and 6
CH.sub.3/100 CH.sub.2 groups, which do not originate from the
comonomers.
[0061] Preference is given to using mixtures of two or more of the
abovementioned ethylene copolymers. More preferably, the polymers
on which the mixtures are based differ in at least one
characteristic. For example, they may contain different comonomers,
or have different comonomer contents, molecular weights and/or
degrees of branching. For example, mixtures of ethylene copolymers
having different comonomer contents have been found to be
particularly useful, the comonomer contents thereof differing by at
least 2 mol % and especially more than 3 mol %.
[0062] The inventive cold additives contain preferably 25 to 95% by
weight and preferably 28 to 80% by weight, for example 35 to 70% by
weight, of at least one organic solvent C). Preferred solvents are
relatively high-boiling, low-viscosity organic solvents. These
solvents preferably contain only minor amounts of heteroatoms, and
they especially consist only of hydrocarbons. Additionally
preferably, the kinematic viscosity thereof, measured at 20.degree.
C., is below 10 mm.sup.2/s and especially below 6 mm.sup.2/s.
[0063] Particularly preferred solvents are aliphatic and aromatic
hydrocarbons and mixtures thereof. Aliphatic hydrocarbons preferred
as solvents have 9 to 20 carbon atoms and especially 10 to 16
carbon atoms. They may be linear, branched and/or cyclic. They may
also be saturated or unsaturated; they are preferably saturated or
at least very substantially saturated. Aromatic hydrocarbons
preferred as solvents have 7 to 20 carbon atoms and especially 8 to
16, for example 9 to 13, carbon atoms. Preferred aromatic
hydrocarbons are mono-, di-, tri- and polycyclic aromatics. In a
preferred embodiment, these bear one or more, for example two,
three, four, five or more, substituents. In the case of a plurality
of substituents, these may be the same or different. Preferred
substituents are alkyl radicals having 1 to 20 and especially
having 1 to 5 carbon atoms, for example methyl, ethyl, n-propyl,
isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl,
tert-pentyl and neopentyl radical. Examples of suitable aromatics
are alkylbenzenes and alkylnaphthalenes. Particularly suitable
examples are aliphatic and/or aromatic hydrocarbons or hydrocarbon
mixtures, for example gasoline fractions, kerosene, decane,
pentadecane, toluene, xylene, ethylbenzene, or commercial solvent
mixtures such as Solvent Naphtha, Shellsoll.RTM. AB, Solvesso.RTM.
150, Solvesso.RTM. 200, Exxsol.RTM., ISOPAR.RTM. and Shellsol.RTM.
D products. The solvent mixtures specified contain different
amounts of aliphatic and/or aromatic hydrocarbons. The solvent C)
may optionally also contain polar solubilizers, for example
alcohols, organic acids, ethers and/or esters of organic acids.
Preferred solubilizers have 4 to 24 carbon atoms, more preferably 6
to 18 and especially 8 to 16 carbon atoms. Examples of suitable
solubilizers are butanol, 2-ethylhexanol, decanol, isodecanol,
isotridecanol, nonylphenol, benzoic acid, oleic acid, dihexyl
ether, dioctyl ether, 2-ethylhexyl acid butyrate, ethyl octanoate,
ethyl hexanoate, butyl 2-ethylhexanoate and 2-ethylhexyl butyrate,
and higher ethers and/or higher esters, for example
di(2-ethylhexyl) ether, 2-ethylhexyl 2-ethylhexanoate and
2-ethylhexyl stearate. The proportion of polar solubilizers in the
solvent C) is preferably 5 to 80% by weight and especially 10 to
65% by weight. In addition to the solvents based on mineral oils,
other suitable solvents C) are those based on renewable raw
materials, for example biodiesel based on vegetable oils and the
methyl esters derived therefrom, especially rapeseed oil methyl
ester, and synthetic hydrocarbons obtainable, for example, from the
Fischer-Tropsch process. Mixtures of the solvents mentioned are
also suitable.
[0064] The inventive cold additives contain preferably 1.5 to
73.5%, particularly 15 to 70% and especially 25 to 60% by weight of
constituent B).
[0065] The inventive cold additives contain preferably 0.1 to 50%,
particularly 0.5 to 30% and especially 1 to 20% by weight of
constituent A).
[0066] The inventive cold additives are added to middle distillates
preferably in amounts of 0.001 to 1.0% by weight, more preferably
0.002 to 0.5% by weight, for example 0.005 to 0.2% by weight.
[0067] The inventive cold additives can be used together with one
or more further cold flow improvers. They are preferably used
together with one or more of cold flow improvers III) to VII):
[0068] Further suitable cold flow improvers are oil-soluble polar
nitrogen compounds (constituent III). These are preferably reaction
products of fatty amines with compounds which contain an acyl
group. The preferred amines are compounds of the formula
NR.sup.6R.sup.7R.sup.8 in which R.sup.6, R.sup.7 and R.sup.8 may be
the same or different, and at least one of these groups is
C.sub.8-C.sub.36-alkyl, C.sub.6-C.sub.36-cycloalkyl or
C.sub.5-C.sub.36-alkenyl, especially C.sub.12-C.sub.24-alkyl,
C.sub.12-C.sub.24-alkenyl or cyclohexyl, and the remaining groups
are hydrogen, C.sub.1-C.sub.36-alkyl, C.sub.2-C.sub.36-alkenyl,
cyclohexyl or a group of the formulae -(A-O).sub.x-E or
--(CH.sub.2).sub.k--NYZ in which A is an ethyl or propyl group, x
is from 1 to 50, E=H, C.sub.1-C.sub.30-alkyl,
C.sub.5-C.sub.12-cycloalkyl or C.sub.6-C.sub.30-aryl, and k=2, 3 or
4, and Y and Z are each independently H, C.sub.1-C.sub.30-alkyl or
-(A-O).sub.x. The alkyl and alkenyl radicals may each be linear or
branched and contain up to two double bonds. They are preferably
linear and substantially saturated, i.e. they have iodine numbers
of less than 75 g of I.sub.2/g, preferably less than 60 g of
I.sub.2/g and especially between 1 and 10 g of I.sub.2/g.
Particular preference is given to secondary fatty amines in which
two of the R.sup.6, R.sup.7 and R.sup.8 groups are each
C.sub.8-C.sub.36-alkyl, C.sub.6-C.sub.36-cycloalkyl,
C.sub.8-C.sub.36-alkenyl, especially C.sub.12-C.sub.24-alkyl,
C.sub.12-C.sub.24-alkenyl or cyclohexyl, and the third is hydrogen.
Suitable fatty amines are, for example, octylamine, decylamine,
dodecylamine, tetradecylamine, hexadecylamine, octadecylamine,
eicosylamine, behenylamine, didecylamine, didodecylamine,
ditetradecylamine, dihexadecylamine, dioctadecylamine,
dieicosylamine, dibehenylamine and mixtures thereof. The amines
especially contain chain cuts based on natural raw materials, for
example coconut fatty amine, tallow fatty amine, hydrogenated
tallow fatty amine, dicoconut fatty amine, ditallow fatty amine and
di(hydrogenated tallow fatty amine). Particularly preferred amine
derivatives are amine salts, imides and/or amides, for example
amide-ammonium salts of secondary fatty amines, especially of
dicoconut fatty amine, ditallow fatty amine and distearylamine.
[0069] Acyl group is understood here to mean a functional group of
the following formula:
.ltoreq.C.dbd.O
[0070] Carbonyl compounds suitable for the reaction with amines are
either monomeric or polymeric compounds having one or more carboxyl
groups. Preference is given to those monomeric carbonyl compounds
having 2, 3 or 4 carbonyl groups. They may also contain heteroatoms
such as oxygen, sulfur and nitrogen. Suitable carboxylic acids are,
for example, maleic acid, fumaric acid, crotonic acid, itaconic
acid, succinic acid, C.sub.1-C.sub.40-alk(en)ylsuccinic acid,
adipic acid, glutaric acid, sebacic acid and malonic acid, and also
benzoic acid, phthalic acid, trimellitic acid and pyromellitic
acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid and
their reactive derivatives, for example esters, anhydrides and acid
halides. Useful polymeric carbonyl compounds have been found to be
especially copolymers of ethylenically unsaturated acids, for
example acrylic acid, methacrylic acid, maleic acid, fumaric acid
and itaconic acid; particular preference is given to copolymers of
maleic anhydride. Suitable comonomers are those which impart oil
solubility to the copolymer. Oil-soluble means here that the
copolymer, after reaction with the fatty amine, dissolves without
residue in the middle distillate to be additized in practically
relevant dosages. Suitable comonomers are, for example, olefins,
alkyl esters of acrylic acid and methacrylic acid, alkyl vinyl
esters and alkyl vinyl ethers each having 2 to 75, preferably 4 to
40 and especially 8 to 20 carbon atoms in the alkyl radical. In the
case of olefins, the carbon number is based on the alkyl radical
attached to the double bond. The molecular weights of the polymeric
carbonyl compounds are preferably between 400 and 20 000, more
preferably between 500 and 10 000, for example between 1000 and
5000.
[0071] It has been found that particularly useful oil-soluble polar
nitrogen compounds are those which are obtained by reaction of
aliphatic or aromatic amines, preferably long-chain aliphatic
amines, with aliphatic or aromatic mono-, di-, tri- or
tetracarboxylic acids or their anhydrides (cf. U.S. Pat. No.
4,211,534). Equally suitable as oil-soluble polar nitrogen
compounds are amides and ammonium salts of
aminoalkylenepolycarboxylic acids such as nitrilotriacetic acid or
ethylenediamine-tetraacetic acid with secondary amines (cf. EP-A-0
398 101). Other oil-soluble polar nitrogen compounds are copolymers
of maleic anhydride and .alpha.,.beta.-unsaturated compounds which
may optionally be reacted with primary monoalkylamines and/or
aliphatic alcohols (cf. EP-A-0 154 177, EP-A-0 777 712), the
reaction products of alkenyl-spiro-bislactones with amines (cf.
EP-A-0 413 279 B1) and, according to EP-A-0 606 055 A2, reaction
products of terpolymers based on .alpha.,.beta.-unsaturated
dicarboxylic anhydrides, .alpha.,.beta.-unsaturated compounds and
polyoxyalkylene ethers of lower unsaturated alcohols.
[0072] The mixing ratio between the inventive cold additives A) and
oil-soluble polar nitrogen compounds as constituent III may vary
depending upon the application. Such additive mixtures preferably
contain, based on the active ingredients, 0.1 to 10 parts by
weight, preferably 0.2 to 5 parts by weight, of at least one
oil-soluble polar nitrogen compound (constituent III) per part by
weight of the inventive additive combination of A) and B).
[0073] Other preferred further cold flow improvers are resins of
phenol derivatives bearing alkyl radicals and aldehydes as
constituent IV. In a preferred embodiment of the invention, they
are phenol-formaldehyde resins which contain oligo- or polymers
with a repeat structural unit of the formula
##STR00003##
in which R.sup.11 is C.sub.1-C.sub.200-alkyl or -alkenyl,
O--R.sup.10 or O--C(O)--R.sup.10, R.sup.10 is
C.sub.1-C.sub.200-alkyl or -alkenyl and h is a number from 2 to
100. R.sup.10 is preferably C.sub.1-C.sub.20-alkyl or -alkenyl and
especially C.sub.4-C.sub.16-alkyl or -alkenyl, for example
C.sub.6-C.sub.12-alkyl or -alkenyl. R.sup.11 is more preferably
C.sub.1-C.sub.20-alkyl or -alkenyl and especially
C.sub.4-C.sub.16-alkyl or -alkenyl, for example
C.sub.6-C.sub.12-alkyl or -alkenyl. h is preferably a number from 2
to 50 and especially a number from 3 to 25, for example a number
from 5 to 15.
[0074] In a particularly preferred embodiment, constituent IV
comprises those resins which derive from alkylphenols having one or
two alkyl radicals in ortho and/or para positions to the OH group.
Particularly preferred starting materials are alkylphenols which
bear, on the aromatic, at least two hydrogen atoms capable of
condensation with aldehydes, and especially monoalkylated phenols.
The alkyl radical is more preferably in the para position to the
phenolic OH group. The alkyl radicals (for constituent IV, this
refers generally to hydrocarbon radicals as defined below) may be
the same or different in the alkylphenol-aldehyde resins usable in
the process according to the invention, they may be saturated or
unsaturated and have 1-200, preferably 1-20, especially 4-16, for
example 6-12, carbon atoms; they are preferably n-, iso- and
tert-butyl, n- and isopentyl, n- and isohexyl, n- and isooctyl, n-
and isononyl, n- and isodecyl, n- and isododecyl, tetradecyl,
hexadecyl, octadecyl, tripropenyl, tetrapropenyl, poly(propenyl)
and poly(isobutenyl) radicals. In a preferred embodiment, the
alkylphenol resins are prepared by using mixtures of alkylphenols
with different alkyl radicals. For example, resins based firstly on
butylphenol and secondly on octyl-, nonyl- and/or dodecylphenol in
a molar ratio of 1:10 to 10:1 have been found to be particularly
useful.
[0075] Resins suitable as constituent IV may also contain or
consist of structural units of further phenol analogs such as
salicylic acid, hydroxybenzoic acid, aminophenol and derivatives
thereof, such as esters, amides and salts.
[0076] Suitable aldehydes for the preparation of the resins are
those having 1 to 12 carbon atoms and preferably having 1 to 4
carbon atoms, for example formaldehyde, acetaldehyde,
propionaldehyde, butyraldehyde, 2-ethylhexanal, benzaldehyde,
glyoxalic acid and their reactive equivalents such as
paraformaldehyde and trioxane. Particular preference is given to
formaldehyde in the form of paraformaldehyde and especially
formalin.
[0077] The molecular weight of suitable resins, measured by means
of gel permeation chromatography against poly(styrene) standards in
THF, is preferably 500-25 000 g/mol, more preferably 800-10 000
g/mol and especially 1000-5000 g/mol, for example 1500-3000 g/mol.
A prerequisite here is that the resins are oil-soluble at least in
concentrations relevant to use of 0.001 to 1% by weight.
[0078] These resins are obtainable by known processes, for example
by condensation of the corresponding phenol derivatives bearing
alkyl radicals with formaldehyde. Suitable further cold flow
improvers are also comb polymers. Such comb polymers (constituent
V) can be described, for example, by the formula
##STR00004##
[0079] In this formula, [0080] A is R', COOR', OCOR', R''--COOR',
OR'; [0081] D is H, CH.sub.3, A or R''; [0082] E is H, A; [0083] G
is H, R'', R''--COOR', an aryl radical or a heterocyclic radical;
[0084] M is H, COOR'', OCOR'', OR'', COOH; [0085] N is H, R'',
COOR'', OCOR, an aryl radical; [0086] R' is a hydrocarbyl chain
having 8 to 50 carbon atoms; [0087] R'' is a hydrocarbyl chain
having 1 to 10 carbon atoms; [0088] a is a number between 0.4 and
1.0; and [0089] b is a number between 0 and 0.6.
[0090] These are especially addition polymers obtainable by
free-radical polymerization with C--C bond formation between the
monomers. Suitable comb polymers are, for example, copolymers of
ethylenically unsaturated dicarboxylic acids such as maleic acid or
fumaric acid with other ethylenically unsaturated monomers such as
olefins or vinyl esters, for example vinyl acetate. Particularly
suitable olefins are .alpha.-olefins having 10 to 36 carbon atoms
and especially having 12 to 24 carbon atoms, for example 1-decene,
1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and mixtures
thereof. Also suitable as comonomers are longer-chain olefins based
on oligomerized C.sub.2-C.sub.6-olefins, for example
poly(isobutylene) with a high proportion of terminal double bonds.
These copolymers are typically esterified to an extent of at least
50% with alcohols having 10 to 22 carbon atoms. Suitable alcohols
include n-decan-1-ol, n-dodecan-1-ol, n-tetradecan-1-ol,
n-hexadecan-1-ol, n-octadecan-1-ol, n-eicosan-1-ol and mixtures
thereof. Particular preference is given to mixtures of
n-tetradecan-1-ol and n-hexadecan-1-ol. Likewise suitable as comb
polymers are poly(alkyl acrylates), poly(alkyl methacrylates) and
poly(alkyl vinyl ethers) which derive from alcohols having 12 to 20
carbon atoms, and poly(vinyl esters) which derive from fatty acids
having 12 to 20 carbon atoms.
[0091] Likewise suitable as further cold flow improvers are homo-
and copolymers of olefins having 2 to 30 carbon atoms (constituent
VI). These may derive directly from monoethylenically unsaturated
monomers or be prepared indirectly by hydrogenation of polymers
which derive from polyunsaturated monomers such as isoprene or
butadiene. Preferred copolymers contain, as well as ethylene,
structural units which derive from .alpha.-olefins having 3 to 24
carbon atoms and have molecular weights of up to 120 000 g/mol.
Preferred .alpha.-olefins are propylene, butene, isobutene,
n-hexene, isohexene, n-octene, isooctene, n-decene, isodecene. The
comonomer content of olefins is preferably between 15 and 50 mol %,
more preferably between 20 and 35 mol % and especially between 30
and 45 mol %. These copolymers may also contain small amounts, for
example up to 10 mol %, of further comonomers, for example
nonterminal olefins or nonconjugated olefins. Particular preference
is given to ethylene-propylene copolymers. Additionally preferred
are copolymers of different olefins having 5 to 30 carbon atoms,
for example poly(hexene-co-decene). The olefin homo- and copolymers
can be prepared by known methods, for example by means of Ziegler
or metallocene catalysts.
[0092] Further suitable olefin copolymers are block copolymers
which contain blocks of olefinically unsaturated, aromatic monomers
A and blocks of hydrogenated polyolefins B. Particularly suitable
block copolymers are those of the (AB).sub.cA and (AB).sub.d
structure where c is a number between 1 and 10 and d is a number
between 2 and 10.
[0093] Likewise suitable as further cold flow improvers are
oil-soluble polyoxyalkylene compounds (constituent VII), for
example esters, ethers and ether/esters of polyols, which bear at
least one alkyl radical having 12 to 30 carbon atoms. In a
preferred embodiment, the oil-soluble polyoxyalkylene compounds
possess at least 2, for example 3, 4 or 5, aliphatic hydrocarbon
radicals. These radicals preferably independently possess 16 to 26
carbon atoms, for example 17 to 24 carbon atoms. These radicals of
the oil-soluble polyoxyalkylene compounds are preferably linear.
Additionally preferably, they are very substantially saturated, and
are especially alkyl radicals. Esters are particularly
preferred.
[0094] Polyols which are particularly suitable in accordance with
the invention are polyethylene glycols, polypropylene glycols,
polybutylene glycols and copolymers thereof with a molecular weight
of approx. 100 to approx. 5000 g/mol, preferably 200 to 2000 g/mol.
In a particularly preferred embodiment, the oil-soluble
polyoxyalkylene compounds derive from polyols having 3 or more OH
groups, preferably from polyols having 3 to about 50 OH groups, for
example 4 to 10 OH groups, especially from neopentyl glycol,
glycerol, trimethylolethane, trimethylolpropane, sorbitan,
pentaerythritol, and the oligomers which are obtainable therefrom
by condensation and have 2 to 10 monomer units, for example
polyglycerol. Also suitable as polyols are higher polyols, for
example sorbitol, sucrose, glucose, fructose and oligomers thereof,
for example cyclodextrin, provided that the esterified or
etherified alkoxylates thereof are oil-soluble at least in
application-relevant amounts. Preferred polyoxyalkylene compounds
thus have a branched polyoxyalkylene core to which a plurality of
alkyl radicals which impart oil solubility are bonded.
[0095] The polyols are generally reacted with 3 to 70 mol of
alkylene oxide, preferably 4 to 50 mol and especially 5 to 20 mol
of alkylene oxide per hydroxyl group of the polyol. Preferred
alkylene oxides are ethylene oxide, propylene oxide and/or butylene
oxide. The alkoxylation is effected by known processes.
[0096] The fatty acids suitable for the esterification of the
alkoxylated polyols have preferably 12 to 30 and especially 16 to
26 carbon atoms. Suitable fatty acids are, for example, lauric
acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic
acid, margaric acid, stearic acid, isostearic acid, arachic acid
and behenic acid, oleic acid and erucic acid, palmitoleic acid,
myristoleic acid, ricinoleic acid, and fatty acid mixtures obtained
from natural fats and oils. Preferred fatty acid mixtures contain
more than 50 mol % of fatty acids having at least 20 carbon atoms.
Preferably less than 50 mol % of the fatty acids used for
esterification contain double bonds, particularly less than 10 mol
%; they are especially very substantially saturated. The
esterification may also proceed from reactive derivatives of the
fatty acids, such as esters with lower alcohols (e.g. methyl or
ethyl esters) or anhydrides.
[0097] In the context of the present invention, "very substantially
saturated" is understood to mean an iodine number of the fatty acid
used or of the fatty alcohol used of up to 5 g of l per 100 g of
fatty acid or fatty alcohol.
[0098] Polyol and fatty acid are used for the esterification, based
on the content of hydroxyl groups on the one hand and carboxyl
groups on the other hand, in a ratio of 1.5:1 to 1:1.5, preferably
in a ratio of 1.1:1 to 1:1.1 and especially in equimolar amounts.
The acid number of the esters formed is generally less than 15 mg
KOH/g, preferably less than 10 mg KOH/g, especially less than 5 mg
KOH/g. The OH number of the esters is preferably less than 20 mg
KOH/g and especially less than 10 mg KOH/g.
[0099] In a preferred embodiment, after the alkoxylation of the
polyol, the terminal hydroxyl groups are converted to terminal
carboxyl groups, for example by oxidation or by reaction with
dicarboxylic acids. Reaction with fatty alcohols having 8 to 50,
particularly 12 to 30 and especially 16 to 26 carbon atoms likewise
affords inventive polyoxyalkylene esters. Preferred fatty alcohols
or fatty alcohol mixtures contain more than 50 mol % of fatty
alcohols having at least 20 carbon atoms. Preferably less than 50
mol % of the fatty alcohols used for esterification contain double
bonds, particularly less than 10 mol %; they are especially very
substantially saturated. Esters of alkoxylated fatty alcohols with
fatty acids, which contain abovementioned proportions of
poly(alkylene oxides) and whose fatty alcohol and fatty acid
possess abovementioned alkyl chain lengths and degrees of
saturation, are also suitable in accordance with the invention.
[0100] In addition, the above-described alkoxylated polyols can be
converted to polyoxyalkylene compounds suitable in accordance with
the invention by etherification with fatty alcohols having 8 to 50,
particularly 12 to 30 and especially 16 to 26 carbon atoms. The
fatty alcohols preferred for this purpose are linear and very
substantially saturated. The etherification is preferably effected
completely or at least very substantially completely. The
etherification is performed by known processes.
[0101] Particularly preferred polyoxyalkylene compounds derive from
polyols having 3, 4 and 5 OH groups, which bear about 5 to 10 mol
of structural units derived from ethylene oxide per hydroxyl group
of the polyol and are very substantially completely esterified with
very substantially saturated C.sub.17-C.sub.24 fatty acids. Further
particularly preferred polyoxyalkylene compounds are polyethylene
glycols which have been esterified with very substantially
saturated C.sub.17-C.sub.24 fatty acids and have molecular weights
of about 350 to 1000 g/mol. Examples of particularly suitable
polyoxyalkylene compounds are polyethylene glycols which have been
esterified with stearic acid and especially behenic acid and have
molecular weights between 350 and 800 g/mol; neopentyl glycol
14-ethylene oxide distearate (neopentyl glycol which has been
alkoxylated with 14 mol of ethylene oxide and then esterified with
2 mol of stearic acid) and especially neopentyl glycol 14-ethylene
oxide dibehenate; glycerol 20-ethylene oxide tristearate, glycerol
20-ethylene oxide dibehenate and especially glycerol 20-ethylene
oxide tribehenate; trimethylolpropane 22-ethylene oxide
tribehenate; sorbitan 25-ethylene oxide tristearate, sorbitan
25-ethylene oxide tetrastearate, sorbitan 25-ethylene oxide
tribehenate and especially sorbitan 25-ethylene oxide
tetrabehenate; pentaerythritol 30-ethylene oxide tribehenate,
pentaerythritol 30-ethylene oxide tetrastearate and especially
pentaerythritol 30-ethylene oxide tetrabehenate and pentaerythritol
20-ethylene oxide 10-propylene oxide tetrabehenate.
[0102] The mixing ratio between the inventive cold additives and
the further cold flow improvers IV, V, VI and VII is generally in
each case between 50:1 and 1:1, preferably between 10:1 and 2:1 by
weight, based on the weights of (A+B):(IV, V, VI and VII).
[0103] The inventive cold additives improve especially the cold
properties of those middle distillates which are obtained by
distillation of crude oil and boil in the range from about 150 to
410.degree. C. and especially in the range from about 170 to
380.degree. C., or consist predominantly thereof, for example
kerosene, jet fuel, diesel and heating oil. Middle distillates
typically contain about 5 to 50% by weight, for example about 10 to
35% by weight, of n-paraffins, among which the longer-chain
paraffins can crystallize out in the course of cooling and impair
the flowability of the middle distillate. The inventive cold
additives are particularly advantageous in middle distillates
having a high content of cold-critical constituents with an n-alkyl
chain having a carbon chain length of 16 or more carbon atoms.
Examples of these include n-paraffins of fossil origin, but also
n-paraffins which have been obtained by hydrogenation or
cohydrogenation of animal and/or vegetable fats, and esters of
saturated fatty acids with lower alcohols such as methanol or
ethanol. Particularly in middle distillates having a content of
more than 4% by weight and especially with 6 to 20% by weight, for
example with 7 to 15% by weight, of these cold-critical
constituents, the inventive cold additives have been found to be
particularly useful. The inventive cold additives are additionally
particularly advantageous in those oils which contain only a very
low proportion of very long-chain n-paraffins having 28 or more
carbon atoms, which function as natural nucleators for paraffin
crystallization. The inventive cold additives have been found to be
especially useful in oils which contain less than 1% by weight and
especially less than 0.5% by weight, for example less than 0.3% by
weight, of long-chain n-paraffins having 28 or more carbon atoms.
Specific advantages are exhibited by the inventive cold additives
especially in those oils which contain a high content of
cold-critical constituents with an n-alkyl chain having 16 or more
carbon atoms, and at the same time a very low proportion of very
long-chain n-paraffins having 28 or more carbon atoms. The content
of n-paraffins and any further cold-critical components, for
example fatty acid methyl esters, is typically determined by means
of gas chromatography. The inventive compositions are additionally
particularly advantageous in middle distillates with a low final
boiling point, i.e. in those middle distillates which have 90%
distillation points below 360.degree. C., especially 350.degree. C.
and in special cases below 340.degree. C., and additionally in
those middle distillates which have boiling ranges between 20 and
90% distillation volume of less than 120.degree. C. and especially
of less than 110.degree. C. The middle distillates may also contain
minor amounts, for example up to 40% by volume, preferably 1 to 20%
by volume, especially 2 to 15%, for example 3 to 10% by volume, of
the oils of animal and/or vegetable origin described in detail
below, for example fatty acid methyl esters. The middle distillates
preferably do not contain any residues from the distillation of
mineral oils, for example residues from atmospheric distillation
and/or vacuum distillation.
[0104] The inventive cold additives are likewise suitable for
improving the cold properties of fuels based on renewable raw
materials (biofuels). Biofuels are understood to mean oils which
are obtained from animal material and preferably from vegetable
material or both, and derivatives thereof, which can be used as a
fuel and especially as a diesel or heating oil. They are especially
triglycerides of fatty acids having 10 to 24 carbon atoms, and also
the fatty acid esters of lower alcohols, such as methanol or
ethanol, obtainable from them by transesterification.
[0105] Examples of suitable biofuels are rapeseed oil, coriander
oil, soybean oil, cottonseed oil, sunflower oil, castor oil, olive
oil, groundnut oil, corn oil, almond oil, palm kernel oil, coconut
oil, mustard seed oil, bovine tallow, bone oil, fish oils and used
cooking oils. Further examples include oils which derive from
wheat, jute, sesame, shea tree nut, arachis oil and linseed oil.
The fatty acid alkyl esters also known as biodiesel can be derived
from these oils by processes known in the prior art. Rapeseed oil,
which is a mixture of fatty acids esterified with glycerol, is
preferred, since it is obtainable in large amounts and is
obtainable in a simple manner by extractive pressing of rapeseed.
Preference is further given to the likewise widespread oils of
sunflowers, palms and soya, and mixtures thereof with rapeseed
oil.
[0106] Particularly suitable biofuels are lower alkyl esters of
fatty acids. Useful examples here are commercial mixtures of the
ethyl esters, propyl esters, butyl esters and especially methyl
esters of fatty acids having 14 to 22 carbon atoms, for example of
lauric acid, myristic acid, palmitic acid, palmitoleic acid,
stearic acid, oleic acid, elaidic acid, petroselic acid, ricinoleic
acid, eleostearic acid, linoleic acid, linolenic acid, eicosanoic
acid, gadoleic acid, docosanoic acid or erucic acid. Preferred
esters have an iodine number of 50 to 150 and especially of 90 to
125. Mixtures with particularly advantageous properties are those
which contain mainly, i.e. to an extent of at least 50% by weight,
methyl esters of fatty acids having 16 to 22 carbon atoms and 1, 2
or 3 double bonds. The preferred lower alkyl esters of fatty acids
are the methyl esters of oleic acid, linoleic acid, linolenic acid
and erucic acid.
[0107] The inventive cold additives can be used alone or else
together with other coadditives, for example with other pour point
depressants or dewaxing assistants, with detergents, antioxidants,
cetane number improvers, dehazers, demulsifiers, dispersants,
antifoams, dyes, corrosion inhibitors, lubricity additives, sludge
inhibitors, odorants and/or additives for lowering the cloud
point.
[0108] The advantages of the inventive cold additives and the
process which utilizes them lie in a distinct improvement in
intrinsic flowability under cold conditions compared to
corresponding prior art additive combinations, with a simultaneous
improvement in efficacy. For instance, these cold additives, given
the same active ingredient content, can also be used at lower
temperatures than the prior art additives, without needing to be
heated. Alternatively, given the same temperature, more highly
concentrated additives can be used, and so the expenditure for
transport and storage is reduced. In addition, the inventive cold
additives surprisingly exhibit improved efficacy in the improvement
of the cold flow properties of middle distillates. This is all the
more unexpected in that the side chain density of the inventive
comb polymers B) is much lower than in the case of the prior art
comb polymers additionally esterified with fatty acids
(DE-A-1920849, DE-A-2451047). The filterability of the fuel oils
treated with the inventive cold additives is surprisingly also
impaired to a much lesser extent than in the case of additization
with prior art additives under the same conditions.
EXAMPLES
[0109] The .alpha.-olefins used were commercially available
mixtures of 1-alkenes with the specified compositions. The acid
numbers were determined by titration of an aliquot of the reaction
mixture with alcoholic tetra-n-butylammonium hydroxide solution in
xylene/isopropanol. The hydroxyl numbers were determined, after
reaction of the free OH groups of the polymers with isocyanate, by
means of .sup.1H NMR spectroscopy by quantitative determination of
the urethane formed. The values reported are based on the
solvent-free polymers. The molecular weights were determined by
means of lipophilic gel permeation chromatography in THF against
poly(ethylene glycol) standards and detection by means of an RI
detector.
[0110] Polyester A) [0111] A1) Copolymer of equimolar proportions
of C.sub.20/24-alkenylsuccinic anhydride (prepared by thermal
condensation of maleic anhydride with technical C.sub.20/24-olefin
containing, as main constituents, 43% .sub.C.sub.20-, 35% C.sub.22-
and 17% C.sub.24-olefin, with 90% .alpha.-olefins and 7.5% linear
internal olefins) and glycerol. The reactants were heated to
150.degree. C. as a 50% solution in Shellsol AB (relatively
high-boiling aromatic solvent mixture) while stirring until the
acid number remained constant. The water which formed was distilled
off. The acid number of the polymer thus prepared was 7.8 mg KOH/g,
the hydroxyl number 98 mg KOH/g and the weight-average molecular
weight 6100 g/mol. [0112] A2) Copolymer prepared in analogy to
Example A1) from equimolar proportions of
C.sub.20/24-alkenylsuccinic anhydride (prepared by thermal
condensation of maleic anhydride with technical C.sub.20/24-olefin
containing, as main constituents, 43% C.sub.20-, 35% C.sub.22- and
17% C.sub.24-olefin, with 90% .alpha.-olefins and 7.5% linear
internal olefins) and polyglycerol having a mean degree of
condensation of 3. The acid number of the polymer was 6.5 mg KOH/g,
the hydroxyl number 195 ring KOH/g and the weight-average molecular
weight 8700 g/mol. [0113] A3) Copolymer prepared in analogy to
Example A1) from equimolar proportions of
C.sub.26/28-alkenylsuccinic anhydride (prepared by thermal
condensation of maleic anhydride with technical C.sub.26-28-olefin
containing, as main constituents, 57% C.sub.26- and 39% C.sub.28-
and 2.5% C.sub.30+-olefin, with 85% .alpha.-olefins, 4% linear
internal olefins and 9% branched olefins) and glycerol. The acid
number of the polymer was 10.4 mg KOH/g, the hydroxyl number 68 mg
KOH/g and the weight average molecular weight 9100 g/mol. [0114]
A4) Copolymer of equal molar proportions of
C.sub.20/24-alkenylsuccinic anhydride according to Example A1,
glycerol and behenic acid in analogy to polymer G of DE-A-24 51
047. The acid number of the polymer was 15 mg KOH/g, the hydroxyl
number 6 mg KOH/g and the weight-average molecular weight 8300
g/mol (comparative example). [0115] A5) Addition copolymer of
equimolar proportions of maleic anhydride and C.sub.20/24-olefin,
esterified with 2 molar equivalents of behenyl alcohol. The acid
number of the polymer was 9 mg KOH/g, the hydroxyl number 11 mg
KOH/g and the weight-average molecular weight 7900 g/mol
(comparative example)
[0116] Ethylene Copolymers B) [0117] B1) Terpolymer of ethylene,
13.5 mol % of vinyl acetate and 1.5 mol % of vinyl neononanoate,
having a melt viscosity measured at 140.degree. C. of 95 mPas.
[0118] B2) Terpolymer of ethylene, 12 mol % of vinyl acetate and 5
mol % of propene, with a melt viscosity measured at 140.degree. C.
of 200 mPas. [0119] B3) Copolymer of ethylene and 13 mol % of vinyl
acetate, with a melt viscosity measured at 140.degree. C. of 125
mPas. [0120] B4) Terpolymer of ethylene, 12.5 mol % of vinyl
acetate and 4 mol % of 4-methylpentene, with a melt viscosity
measured at 140.degree. C. of 170 mPas.
[0121] The melt viscosity of the ethylene copolymers B) was
determined by means of a rotary viscometer at a temperature of
140.degree. C. Before the measurement, all volatile components were
removed from the ethylene copolymer B) at 150.degree. C./100
mbar.
[0122] Solvents C) [0123] C1) Solvesso.RTM. 150: high-boiling
aromatic mixture (approx. 98% aromatics, 0.7% naphthalene, boiling
range 175-205.degree. C., flashpoint 65.degree. C.) [0124] C2)
White spirit: mixture of mainly paraffinic and naphthenic
hydrocarbons in the C.sub.10 to C.sub.16 range (aromatics content
16%, boiling range 182-212.degree. C., flashpoint 63.degree.
C.)
[0125] To determine the cold properties of the cold additives, the
pour points thereof were determined to DIN ISO 3016. A low pour
point indicates good flowability and hence good manageability under
cold conditions. The percentages reported for the additives relate
to the proportions by weight of the additive constituents used. The
proportions by weight specified for the polymers relate to
solvent-free active ingredients. Any solvent components present in
the polymers as a result of the synthesis are shown as solvent
C).
TABLE-US-00001 TABLE 1 Determination of the pour points Additive
Polyester Polymer B Solvent C Pour Point 1 3.0% A1 47.0% B1 50% C1
-12.degree. C. 2 3.0% A2 47.0% B1 50% C1 -9.degree. C. 3 3.0% A3
47.0% B1 50% C1 -6.degree. C. 4 (comp.) 3.0% A4 47.0% B1 50% C1
+6.degree. C. 5 (comp.) 3.0% A5 47.0% B1 50% C1 +9.degree. C. 6
3.5% A1 31.5% B2 65% C1 -21.degree. C. 7 3.5% A2 31.5% B2 65% C1
-21.degree. C. 8 3.5% A3 31.5% B2 65% C1 -15.degree. C. 9 (comp.)
3.5% A4 31.5% B2 65% C1 -12.degree. C. 10 (comp.) 3.5% A5 31.5% B2
65% C1 -9.degree. C. 11 3.0% A1 32.0% B3 65% C2 -6.degree. C. 12
3.0% A2 32.0% B3 65% C2 -3.degree. C. 13 3.0% A3 32.0% B3 65% C2
-3.degree. C. 14 (comp.) 3.0% A4 32.0% B3 65% C2 +6.degree. C. 15
(comp.) 3.0% A5 32.0% B3 65% C2 +6.degree. C. 16 4.0% A1 56.0% B4
40% C2 -9.degree. C. 17 4.0% A2 56.0% B4 40% C2 -12.degree. C. 18
4.0% A3 56.0% B4 40% C2 -3.degree. C. 19 (comp.) 4.0% A4 56.0% B4
40% C2 +6.degree. C. 20 (comp.) 4.0% A5 56.0% B4 40% C2 +6.degree.
C.
[0126] The efficacy of the additives was studied by means of the
lowering of the CFPP value to DIN EN 116 in low-sulfur middle
distillates having the characteristics shown in Table 2. The
components with n-alkyl radical .gtoreq.C.sub.16 and the
n-paraffins .gtoreq.C.sub.28 were determined by means of gas
chromatography.
TABLE-US-00002 TABLE 2 Characterization of the test oils Test oil 1
Test oil 2 Test oil 3 Initial boiling point [.degree. C.] 171 179
173 Final boiling point [.degree. C.] 355 348 331 Boiling range
(20-90)% [.degree. C.] 93 94 89 Density [g/cm.sup.3] 0.8555 0.8437
0.8409 Cloud point [.degree. C.] -11.7 -15.6 -22.0 CFPP [.degree.
C.] -12 -15 -22 Sulfur content [ppm] <10 <10 <10
Components with n-alkyl [% by wt.] 11.1 9.8 8.3 radical .gtoreq.
C.sub.16 n-Paraffins .gtoreq. C.sub.28 [% by wt.] 0.04 0.11
0.01
TABLE-US-00003 TABLE 3 CFPP efficacy in test oil 1 Additive CFPP
[.degree. C.] Example (according to Tab. 1) 200 ppm 300 ppm 1
(comp.) none -12 -12 2 (comp.) B1 (50% in C1) -14 -20 3 1 -22 -29 4
2 -20 -26 5 3 -23 -28 6 (comp.) 4 (comp.) -18 -25 7 (comp.) 5
(comp.) -17 -25 1 (comp.) none -12 -12
TABLE-US-00004 TABLE 4 CFPP efficacy in test oil 1 Additive CFPP
[.degree. C.] Example (according to Tab. 1) 350 ppm 500 ppm 8
(comp.) none -15 -15 9 (comp.) B2 (35% in C1) -16 -18 10 6 -25 -31
11 7 -25 -30 12 8 -23 -30 13 (comp.) 9 (comp.) -21 -28 14 (comp.)
10 (comp.) -19 -26
TABLE-US-00005 TABLE 5 CFPP efficacy in test oil 2 Additive CFPP
[.degree. C.] Example (according to Tab. 1) 100 ppm 150 ppm 15
(comp.) none -15 -15 16 (comp.) B4 (60% in C2) -17 -21 17 16 -24
-31 18 17 -23 -28 19 18 -23 -30 20 (comp.) 19 (comp.) -20 -26 21
(comp.) 20 (comp.) -20 -24
[0127] For comparison of the solubility of the cold additives, 200
ml of test oil 3 (Table 2) were admixed with 1000 ppm of an
additive according to Table 1 at the temperature specified in Table
6 in a 250 ml measuring cylinder. The additives were added by means
of a direct displacement pipette in order to be able to manage the
high viscosity of the comparative additives in particular. After
rotating the measuring cylinder by 180.degree. ten times, a visual
examination was made for undissolved additive constituents.
TABLE-US-00006 TABLE 6 Solubility of the additives in test oil 3
T.sub.additive Example Additive [.degree. C.] T.sub.oil [.degree.
C.] Appearance 22 1 6 -3 homogeneous, clear 23 2 6 -3 homogeneous,
clear 24 (comp.) 4 (comp.) 6 -3 additive substantially undissolved
25 (comp.) 5 (comp.) 6 -3 additive substantially undissolved 26 6
-12 -20 homogeneous, clear 27 7 -12 -20 homogeneous, clear 28 8 -12
-20 homogeneous, clear 29 (comp.) 9 (comp.) -12 -20 contains many
flakes 30 (comp.) 10 (comp.) -12 -20 additive substantially
undissolved
* * * * *