Note: Descriptions are shown in the official language in which they were submitted.
-` ~2~895
Ethylene Terpolymer Additives for Mineral Oil
and Mineral Oil Distillates
The present invention relates to the use of terpolymers
of ethylene, diisobutylene and vinylacetate to improve the
flowability and the low temperature behaviour of mineral oil and
mineral oil distillates.
Mineral oils such as crude oil, diesel fuel or fuel oil
contain varying amounts of long-chain paraffins (waxes) dissolved
in them which crystallize out at low temperatures. This leads
to solid deposits which often cause breakdowns during the
recovery, transportation and use of such oils. Thus, the
operability of crude oil conveyance and transportation facilities
can be impaired to such a degree that they fail completely. With
diesel engines and firing plants the filter can become blocked,
preventing accurate dosage of the fuels and finally resulting in
a complete breakdown of the equipment.
This undesirable formation of solid deposits is
counteracted by additives which prevent the paraffin crystals
from forming and stop the viscosity of the oils from increasing.
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The flow and low temperature behaviour of mineral oils
and mineral oil distillates is measured by the pour point and the
cold filter plugging point (CFP point). The pour point
(determined in accordance with DIN 51 597) is the lowest
temperature at which a mineral oil or mineral oil distillate can
still just flow. The cold filter plugging point (determined in
accordance with DIN 51 428) represents the limit of
filterability. For economic reasons it is of interest to find
one single additive which favorably influences both the pour
point and the cold filter plugging point.
Typical pour point reducers and flow improvers for
crude oils and middle distillates are ethylene copolymers with
carboxylic acid esters of vinyl alcohol. Of these copolymers
ethylene/vinylacetate has proved to be particularly successful.
Such copolymers and their applications are described, for
example, in DE-PS 1 914 756. They are generally produced by
copolymerization of the corresponding monomers in autoclaves at
temperatures of 80 to 150 C and pressures of 5 to 15 MPa in the
presence of peroxides as initiators and organic solvents as
reaction media.
A disadvantage of the ethylene/vinylacetate copolymers
is that, although they improve the CFP point of middle
distillates, they only slightly reduce the pour point.
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The task therefore consisted in preparing additives for
mineral oils which appreciably reduce both the CFP point and the
pour point.
The invention consists in the use of terpolymers which
not only contain ethylene but also 0.5 to 20% by weight
diisobutylene and 20 to 35% by weight vinylacetate and which have
an average molecular weight of 500 to lo,oOo as additives in
mineral oils and mineral oil distillates.
Surprisingly, the problem is solved by the use of the
particular terpolymers of the present invention. It was
impossible to fore6ee that terpolymers of ethylene, diisobutylene
and vinylacetate would appreciably reduce kQ~h the CFP point and
the pour point of mineral oils and mineral oil distillates.
It is recognized that terpolymers of ethylene,
isoolefins (in particular isobutene), and vinylacetate as such
are known as flow improvers from the EP 0 099 646 Al. However,
these products nave little effect as both pour point and CFP
point reducer6. The ethylene terpolymers employed in accordance
with the invention contain 0.5 to 20% by weight diisobutylene.
Terpolymers wherein the proportion of Co-olefins is l to 15% by
weight (based on the terpolymer) have proven to be particularly
successful.
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12~18g5
In the terpolymer employed in accordance with the
invention, the proportion of vinylacetate is 20 to 35% by weight,
a proportion of 22 to 30% by weight is preferred, based on the
terpolymer.
The average molecular weight of the terpolymers of the
invention, measured in a steam phase osmometer with toluene as
a solvent, is 500 to 10,000; polymers with a molecular weight of
1,000 to 5,000 are preferred.
In another preferred embodiment of the invention
terpolymerisates are used whose melt viscosity (measured at
140C) is 100 to 1,OOo mPa x sec. The melt viscosity is
determined in a rotation viscosimeter in accordance with the
German Standard DIN 53019.
The ethylene/diisobutylene(vinylacetate terpolymers
contain branchings which are due to the incorporation of
diisobutylene and ethylene in the macromolecule. For every lOo
CH2 groups, the terpolymers carry 6 to 20 CH3 groups in the side
chains and which do not originate from the vinylacetate. In
accordance with the invention, the terpolymers preferably contain
7 to 15 C%3 groups in the side chains per 100 CH2 groups.
The terpolymers which are employed in accordance with
the invention are prepared from mixtures of ethylene,
diisobutylene, and vinylacetate which are polymerized in the
presence of radical-forming initiators (such as peroxides)
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1271895
at pressures above 50 mPa and at temperatures of 150 to 350~c in
the absence of organic solvents. The molecular weights of the
terpolymers are preferably determined by the diisobutylene.
Other molecular weight controllers such as hydrocarbons,
aldehydes and ketones can also be used; however, they should be
present in amounts of 1 to 5% by weight based on the monomer
mixture. Propionaldehyde is particularly suitable as a molecular
weight controller. Monomer mix~ures containing 79 to 20% by
weight ethylene, 1 to 40% by weight diisobutylene and 20 to 40%
by weight vinylacetate are among those suitable for
polymerization.
Generally speaking, the terpolymer is added to the
mineral oils or mineral oil fractions in the form of a 40 to 60%
by weight solution in an aliphatic or aromatic hydrocarbon or in
a hydrocarbon mixture. Kerosene has, for example, proven to be
very suitable as a solvent. The amount of polymer based on the
mineral oil or mineral oil fraction should be 0.001 to 2%,
preferably 0.005 to 0.5%, by weight. The terpolymer can be used
alone or together with other additives; for example, with
dewaxing agents, corrosion inhibitors, antioxidants or sediment
inhibitors.
The use of ethylene/diisobutylene/vinylacetate
terpolymers according to the invention as additives for mineral
oils and mineral oil distillates is explained in detail in the
following examples: -
-6-
`~ 127~89~;
Examples A - C relate to the manufacture and properties
of ethylene/diisobutylene/vinylacetate terpolymers. Examples D -
F describe the manufacture and properties of polymers which are
cited as comparative substances. Data on the efficiency of the
terpolymers employed as additives in mineral oil and mineral oil
distillates in accordance with the invention are compiled in
examples 1 - 3. The data are compared with the figures obtained
for the comparative substances in examples 4 - 6.
0 Examples A - C: Manufacture of Ethylene/diisobutylene
Vinylacetate Ter~olymers.
Ethylene, diisobutylene (technical diisobutylene with
about 75% by weight 2,4,4-trimethylenpentene-1) and vinylacetate
are continuously polymerized in an autoclave. The monomer
mixture is fed into the autoclave at the reaction pressure after
the amount of peroxide required to maintain polymerization has
been added as a solution in a petrol fraction. The residence
period is about 80 seconds. The manufacture of the terpolymers
listed in examples D - F takes place in the same manner. The
polymerization conditions used and the characteristic properties
of the polymers obtained are listed in Table 1.
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1~1895
The vinylacetate content of the polymers is determined
by the pyrolysis method. This involves taking 200 mg of the
polymer and heating it with 300 mg of pure polyethylene in a
pyrolysis flask for 5 minutes to a temperature of 450~C. The
cracked gases are collected in a 250ml round flask. The acetic
acid formed is reacted with a NaI/KIO3 solution and the iodine
thus released is titrated with a Na2S2O3 solution.
The degree of branching of the polymers is determined
by means of H-NMR spectroscopy. In the following examples, the
degree of branching is understood to be the number of CH3 groups
per 100 CH2 groups, except for those CH3 groups which originate
with the acetate group. The viscosity is measured with a
Rotovisco System MV II (manufacturer: Haake, Karlsruhe) at a
temperature of 140C. The diisobutylene content in the polymer
is determined by means of 13 C-NMR spectroscopy.
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~2~895
~xamples 1 - 6
In the following examples 1 - 6, the ef~iciencies of
the use of various ethylene/diisobutylene/vinylacetate and
ethylene/isobutylene/vinylacetate terpolymers are described as
additives in mineral oils and mineral oil distillates. The CFPP
test (cold filter plugging point) and determination of the pour
points, measure this characteristic. Examples 1 - 3 are
terpolymers in accordance with the invention; examples 4 - 6
relate to terpolymers which are not covered by the invention and
serve as a comparison. The test is performed in accordance with
DIN 51428 and is also published in the Journal of the Institute
of Petroleum, volume 52, June 1966, pages 173 to 185. The pour
point is measured in accordance with DIN 51597.
Three middle distillates M1, M2 and M3 were tested and
their properties compiled in Table 2.
-- 10 --
~9s
TABLE 2
Characteristic data of the middle distillates
M 1 M 2 M3
analysis by boiling (C)
boiling begin 180 209 182
5% 202 281 213
50% 297 289 281
90% 357 356 3~9
boiling end 357 368 370
pour point (C) - 6 - 9
CFPP point (~C) + 1 - 1 - 6
-- 11 --
~2718g5
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-- 12 --
-` ~27~895
The results compiled in Table 3 show that only
waxy terpolymers which contain diisobutylene qualitatively
as a termonomer and 20 to 35% by weight vinylacetate
quantitatively reduce both the pour point and the CFP
point to the extent desired in practice.
