Mixtures of carboxylic acids, their derivatives and...

Details Mixtures of carboxylic acids, their derivatives and... Mixtures of carboxylic acids, their derivatives and...

2001-03-16

2003-07-15

Toomer, Cephia D. (Department: 1714)

Fuel and related compositions

Liquid fuels

Containing organic -cx- compound, wherein the x's are the...

C385S046000, C385S046000, C385S046000, C385S046000, C385S046000, C385S046000, C044S451000, C524S186000, C524S282000, C524S284000, C524S294000, C524S295000, C524S296000, C524S298000, C524S366000, C524S379000

Reexamination Certificate

active

06592638

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an additive which comprises a long-chain carboxylic acid and/or its derivatives and one or more hydroxyl-containing polymers, fuel oils which contain such additives and the use of such additives for improving the lubricity of middle distillates.
BACKGROUND OF THE INVENTION
Mineral oils and mineral oil distillates which are used as fuel oils contain in general 0.5% by weight or more of sulfur, which results in the formation of sulfur dioxide on combustion. To reduce the resulting environmental pollution, the sulfur content of fuel oils is being increasingly reduced. The introduction of standard EN 590 relating to diesel fuels currently prescribes a maximum sulfur content of 350 ppm in Germany. In Scandinavia, fuel oils containing less than 50 ppm and in exceptional cases less than 10 ppm of sulfur are already in use. These fuel oils are produced as a rule by subjecting the fractions obtained from mineral oil by distillation to refinement involving hydrogenation. However, the desulfurization also results in the removal of other substances which impart a natural lubricating effect to the fuel oils. These substances include polyaromatic and polar compounds.
However, it has been found that the friction- and wear-reducing properties of fuel oils deteriorate with an increasing degree of desulfurization. Often, these properties are so poor that corrosion phenomena have to be expected after only a short time on the materials lubricated with fuel, for example the distributor injection pumps of diesel engines. The maximum value of 360° C. for the 95% distillation point specified according to EN 590 since the year 2000 and the further reduction of the 95% distillation point to below 350° C. and in some cases below 330° C., now implemented in Scandinavia, have further intensified these problems.
The prior art therefore describes approaches which are intended to solve this problem (so-called lubricity additives).
EP-A-0 743 974 discloses the use of mixtures of lubricity additives (esters of polyhydric alcohols and carboxylic acids having 10 to 25 carbon atoms or dicarboxylic acids) and flow improvers based on copolymers of ethylene and unsaturated esters for the synergistic improvement of the lubricating effect of highly desulfurized oils.
EP-A-0 802 961 discloses fuel oils which contain at least one hydroxylamine for improving their lubricating effect.
WO-99/36 489 discloses the use of mixtures of monomeric and polymeric fatty acids for improving the lubricating effect of low-sulfur middle distillates.
DE-A-197 57 830 discloses that hydroxyl-containing polymers can be used as a mixture with acid derivatives. However, no technical advantages of such mixtures are disclosed and furthermore no examples of these are given.
EP-A-0 807 676 discloses a fuel oil additive which increases the lubricity of said fuel oil and which, in addition to a carboxamide, comprises a cold flow improver and an ashless dispersant.
EP-A-0 680 506 discloses the use of esters of monobasic or polybasic carboxylic acids with monohydric or polyhydric alcohols as lubricity additives for fuel oils.
The lubricity additives of the prior art have, as far as polymers are concerned, the disadvantage that, owing to their high viscosity, they have to be used as a solution or dispersion in suitable solvents in order to improve their handling. However, the use of solvents results in increased metering rates and hence in the transport of larger amounts of substances. Owing to their amphiphilic character, the nonpolymeric additives often have a pronounced tendency to emulsify. Consequently, the residual water present in storage tanks is converted into stable emulsions with the middle distillates, which can then lead to problems with respect to corrosiveness and cold flow properties.
SUMMARY OF THE INVENTION
It was thus the object of the present invention to provide additive compositions which have little tendency to emulsify and are also effective when used as additives in small amounts.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Surprisingly, it was found that additive combinations comprising oil-soluble amphiphiles and hydroxyl-containing copolymers have the disadvantages of the prior art in a substantially reduced manner.
The invention relates to additives for improving lubricating properties of fuel oils, comprising
A) 10-95% by weight of at least one oil-soluble amphiphile of the formulae 1
 in which R
1
is an alkyl, alkenyl, hydroxyalkyl or aromatic radical having 1 to 50 carbon atoms, X is NH, NR
3
, O or S, y is 1, 2, 3 or 4, R
2
is hydrogen or an alkyl radical carrying hydroxyl groups and having 2 to 10 carbon atoms and R
3
is an alkyl radical carrying nitrogen and/or hydroxyl groups and having 2 to 10 carbon atoms or a C
1
-C
20
-alkyl radical, and
B) 5-90% by weight of at least one copolymer which contains
B1) from 0.5 to 15 mol % of structural units which are derived from olefinically unsaturated compounds which have at least one free hydroxyl group
B2) from 85 to 99.5 mol % of structural units which are derived from ethylene, and, if required,
B3) from 0 to 20 mol % of further structural units selected from the group consisting of (meth)acrylic acid, (meth)acrylates, vinyl esters, vinyl ethers and alkenes, with the proviso that the structural units stated under B3) differ from the structural units stated under B1) and B2),
and the copolymer has an average molar mass Mw of from 500 to 100,000 g/mol and an OH number of from 5 to 300 mg KOH/g.
The invention furthermore relates to fuel oils which contain said additives.
The invention furthermore relates to the use of the additives for improving the lubricating properties of fuel oils.
The invention furthermore relates to a process for improving the lubricity of fuel oils.
The oil-soluble amphiphile (component A) comprises preferably a radical R
1
having 5 to 40, in particular 12 to 26, carbon atoms. Particularly preferably, R
1
is linear or branched and, in the case of linear radicals, contains from 1 to 3 double bonds. The radical R
2
preferably has 2 to 8, especially 2 to 6 carbon atoms, and may be interrupted by nitrogen and/or oxygen atoms. In a further preferred embodiment, the sum of the carbon atoms of R
1
and R
2
is at least 10, in particular at least 15 and not more than 35, in particular not more than 28, carbon atoms. In a further preferred embodiment, the component A carries from 2 to 5 hydroxyl groups, each carbon atom carrying not more than one hydroxyl group.
In a preferred embodiment of the invention, X in the formula 1 is oxygen. These compounds are in particular fatty acids and esters of carboxylic acids and dihydric or polyhydric alcohols. Preferred esters contain at least 10, in particular at least 12, carbon atoms. It is also preferred if the esters contain free hydroxyl groups, i.e. the esterification of the polyol with the carboxylic acid is not complete. Suitable polyols are, for example, ethylene glycol, diethylene glycol and higher alkoxylation products, glycerol, trimethylolpropane, pentaerythritol and sugar derivatives. Further polyols containing hetero atoms, such as triethanolamine, are also suitable. In a further preferred embodiment of the invention, the compounds which form the component A of the additive are fatty acids having 10 to 22 carbon atoms. These may be saturated or unsaturated.
Preferred components A are straight-chain saturated fatty acids having up to 18 carbon atoms, such as caprylic acid (octanoic acid), capric acid (decanoic acid), lauric acid (dodecanoic acid), myristic acid (tetradecanoic acid), palmitic acid (hexadecanoic acid), stearic acid (octadecanoic acid), and in particular unsaturated fatty acids, such as oleic acid (octadecenoic acid), linoleic acid, linolenic acid and mixtures thereof, such as, for example, rapeseed oil acid, soybean fatty acid, sunflower fatty acid, peanut fatty acid and tall oil fatty acid. Furthermore, dimeric and oligomeric fatty acids, as formed in the oligomerization of unsaturated fatty acids, may be present. Preferably, at

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