Lubricating oil compositions

Details Lubricating oil compositions Lubricating oil compositions

1999-05-21

2001-05-15

McAvoy, Ellen M. (Department: 1764)

Solid anti-friction devices, materials therefor, lubricant or se

Lubricants or separants for moving solid surfaces and...

Organic -co- compound

C508S545000, C508S551000, C508S567000, C508S585000, C508S586000, C044S393000, C044S412000, C044S418000, C044S435000, C044S440000

Reexamination Certificate

active

06232277

ABSTRACT:

This invention relates to improved oil compositions and improved additives therefor, in particular to fuel oil compositions having improved low temperature flow and especially filterability properties, and to additives enhancing a variety of fuel properties and providing operational advantages for fuel manufacturers and users.
Many oil, and particularly fuel oil, compositions suffer from the problem of reduced flowability and/or filterability at low temperatures, due to the precipitation of the heavier alkanes (and particularly n-alkanes) inherent in such oils. This problem of alkane crystallisation at low temperatures is well known in the art. Additive solutions to this problem have been proposed for many years, in particular, copolymers of ethylene and vinyl esters such as vinyl acetate or vinyl propionate have been successfully used in commercial applications and are well documented in the patent literature.
The problem of poor low temperature filterability has conventionally been measured by the Cold Filter Plugging Point (“CFPP”) test, which determines the ease with which fuel moves under suction through a filter grade representative of field equipment. The determination is repeated periodically during steady cooling of the fuel sample, the lowest temperature at which the minimum acceptable level of filterability is still achieved being recorded as the “CFPP” temperature of the sample. The details of the CFPP test and cooling regime are specified in the European Standard method EN116. The CFPP test is acknowledged as a standard bench test for determining fuel performance and, as such, has been adopted in many national fuel specifications. Such specifications set a number of minimum technical requirements for fuels of particular grades, so establishing a minimum quality level below which fuels are not considered technically “fit for purpose”.
Ethylene copolymers have typically been used to achieve the desired CFPP performance of oils, especially middle distillate fuel oils, to such an extent that the use of such copolymers has become a standard refinery practice.
In recent years, other fuel performance requirements have grown in importance. In particular, the degree of settling of precipitating n-alkane crystals has an important influence on the tendency of such crystals to interrupt fuel supply. Other additives, known as “Wax Anti-Settling Additives”, and typically based on oil soluble polar nitrogen-containing compounds, have been developed to reduce the rate of settling of precipitating n-alkanes and so enhance this aspect of fuel low temperature behaviour. Such additives are typically used in conjunction with the conventional CFPP enhancing ethylene polymers.
However, such combined usage has led to a further problem, namely that of “CFPP Regression”. In brief, the addition of a polar nitrogen containing compound can, whilst improving the wax anti-settling character of the fuel, adversely affect the performance of the CFPP enhancing additive. As a notional example, a diesel fuel having a base CFPP (without additive) of −5° C. may, upon addition of an ethylene vinyl acetate copolymer; achieve a CFPP of −15° C. or even lower. Co-addition of a wax anti-settling additive may, whilst giving better dispersion of the crystals, worsen the CFPP for example to −10° C., i.e. a regression of 5° C. The net result of CFPP regression is that the fuel manufacturer may be forced (in order to meet the required minimum CFPP specification) either to use higher quantities of the ethylene polymer in order to offset the regression, or to reduce the amount of wax anti-settling additive and sacrifice settling performance accordingly.
A material has now been found which, when used as a co-additive, reduces or eliminates this problem of CFPP regression and can even enhance the overall CFPP performance of a fuel. Preferred embodiments can also enhance the wax anti-settling additive performance, so allowing the fuel manufacturer greater flexibility in meeting the required low temperature aspects of the fuel specification. The material can, when formulated within an additive composition or concentrate further comprising a polar nitrogen-containing additive, also improve the overall physical compatibility of the additive blend and accordingly reduce the need for high quantities of polar solvent.
Recently, the advent of more stringent fuel oil sulphur specifications has led to a deterioration in fuel oil lubricity.
Environmental concerns have led to a need for fuels with reduced sulphur content, especially diesel fuel and kerosene. However, the refining processes that produce fuels with low sulphur contents also lower the content of other components in the fuel that contribute to its lubricity, for example, polycyclic aromatics and polar compounds. The result, has been an increase in reported failures of fuel pumps in diesel engines using low-sulphur fuels, the failure being caused by wear in, for example, cam plates, rollers, spindles and drive shafts.
This problem may be expected to become worse in future because, in order to meet stricter requirements on exhaust emissions generally, higher pressure fuel pumps and systems, including in-line, rotary and unit injector systems, are being introduced, these being expected to have more stringent lubricity requirements than present equipment.
At present, a typical sulphur content in a diesel fuel is about 0.05% by weight. In Europe maximum sulphur levels are expected to be reduced to 0.035%; in Sweden grades of fuel with levels below 0.005% (Class 2) and 0.001% (Class 1) are already being introduced. A fuel oil composition with a sulphur level below 0.05% by weight is referred to as a low sulphur fuel.
The co-additive material of this invention can also provide enhanced fuel lubricity, reducing or eliminating the need for a conventional lubricity additive whilst enabling the desired (or specified) fuel lubricity performance to be achieved.
Other advantages of the invention will become apparent from the following description.
U.S. Pat. No. 4,446,039 discloses compositions useful as additives for fuels and lubricants, made by reacting certain aromatic compounds such as substituted phenols with aldehyde or the equivalent thereof, non-amino hydrogen, active hydrogen compounds and hydrocarbon based aliphatic alkylating agents.
In a first aspect, this invention provides an additive composition obtainable by admixture of:
(a) At least one ethylene polymer,
(b) The product obtainable by the condensation reaction between:
(i) at least one aldehyde or ketone or reactive equivalent thereof, and
(ii) at least one compound comprising one or more aromatic moieties bearing at least one substituent of the formula —XR
1
and at least one further substituent —R
2
, wherein
X represents oxygen or sulphur,
R
1
represents hydrogen or moiety bearing at least one hydrocarbyl group, and
R
2
represents a hydrocarbyl group and contains less than 18 carbon atoms when a linear group, and
(c) At least one oil soluble polar nitrogen compound different from (b) and comprising one or more substituents of the formula >NR
13
where R
13
represents a hydrocarbyl group containing 8-40 carbon atoms, which substituent or one or more of which substituents may be in the form of a cation derived therefrom:
In a second aspect, the invention provides an additive concentrate comprising either the additive composition of the first aspect, or (a), (b) and (c) as defined in the first aspect, in admixture with a compatible solvent therefore.
In a third aspect, the invention provides a fuel oil composition comprising fuel oil and either the additive or concentrate of the first or second aspect, or (a), (b) and (c) as defined in the first aspect.
In a fourth aspect, the invention provides a process for the manufacture of the fuel oil composition of the third aspect, comprising:
(i) obtaining a fuel oil, and
(ii) blending therewith either the additive or concentrate composition of any preceding claim, or the components (a), (b) and (c) as defined in any preceding claim.
In a fifth

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