Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic compound containing boron
Reexamination Certificate
1998-12-28
2001-08-21
Johnson, Jerry D. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic compound containing boron
C508S185000, C508S391000, C508S586000
Reexamination Certificate
active
06277794
ABSTRACT:
This invention relates to an improved lubricating oil composition for marine applications, such as a marine diesel cylinder lubricant (MDCL) suitable for cross-head diesel engines. More particularly, this invention relates to a finished lubricant formulation exhibiting improved piston ring and liner wear performance.
The lubrication of cross-head diesel engines, in particular the cylinder liners and piston rings of such engines, presents problems because the operating temperatures and pressures can lead to breakdown of the film of lubricant on the internal walls of the cylinder liners. When this occurs, the cylinder liners and/or piston rings may wear excessively.
EP-A-369,804 describes a method of lubricating a cross-head engine which comprises lubricating the engine with a lubricant composition comprising a major amount of base oil and minor amounts of an anti-wear additive and of an extreme-pressure additive. It states that the amount of extreme pressure additive should be sufficient to provide an extreme pressure effect, usually up to 5.0 mass % based on the total weight of the composition. Thus, EP-A-369,804 teaches the need for a combination of an extreme-pressure additive and an anti-wear additive to achieve effectiveness.
The present invention solves the above problem by lubricating a marine diesel engine with at least one ashless anti-wear additive without need for minor amounts of an extreme pressure additive, whilst providing effective anti-wear performance under the high temperature and high pressure conditions of the cylinder liners and piston rings of marine diesel engines; furthermore, EP-A-369,804 describes the use, as co-additives, of overbased 250 TBN calcium phenate in combination with overbased 300 TBN calcium sulfonate. The present invention also provides the particularly effective use of combination with a minor amount of an ashless anti-wear additive.
Accordingly, a first aspect of the present invention is a marine diesel engine lubricant composition having a TBN of at least 10, such as at least 20, and preferably a viscosity index of at least 90, preferably at least 100, more preferably at least 110, the composition comprising, or being provided by admixing, a major amount of oil of lubricating viscosity and a minor amount of
A) an ashless antiwear additive; and
B) a metal detergent in the form of
(i) an overbased metal detergent having a TBN at least 300, preferably at least 330, more preferably at least 400, and comprising a surfactant system derived from at least two surfactants, and/or
(ii) a metal detergent other than (i);
provided that, if detergent (ii) is present, the composition does not contain a minor amount of an extreme pressure additive, being up to 5.0 mass % based on the total mass of the composition.
A second aspect of the present invention is a method of making a marine diesel engine lubricant composition having a TBN of at least 10, such as at least 20, and preferably a viscosity index of at least 90, preferably at least 100, more preferably at least 110, comprising blending a major amount of oil of lubricating viscosity and minor amounts of (A) and (B) as defined in the first aspect of the invention, provided that, if detergent (ii) is blended, a minor amount of an extreme pressure agent, being up to 5.0 mass % based on the total mass of the composition, is not blended.
Preferably, in respect of use of metal detergent (B) (ii), the extreme pressure additive, if used, is not present in an amount up to 5.0, 4, 3, 2 or 1, mass % based on the mass of the lubricant composition. More, preferably, the extreme pressure additive is absent, and is absent also in respect of use of metal detergent (B) (i).
In contrast to antiwear additives, which protect against friction and wear under moderate boundary conditions, an extreme-pressure additive prevents the welding of mating surfaces that occurs at the exceedingly high local temperatures developed when opposing bodies are rubbed together under sufficient load. The latter form of protection is effective only under conditions of high local temperature. Thus, an extreme-pressure additive is essentially an extreme-temperature additive. The aforementioned EP-A-369,804 describes extreme pressure additives, as does J. A. Williams in “Engineering Tribology” (Oxford University Press, 1994), ps 354-357. The latter reference states that the real function of extreme-pressure additives is to lubricate at comparatively high temperatures, perhaps up to as much as 300-400° C.; in contrast, anti-wear additives lubricate at lower temperatures and, according to the latter reference, act in a different way.
A third aspect of the present invention is a marine diesel engine lubricant composition comprising, or being provided by admixing, a major amount of oil of lubricating viscosity and a minor amount of (A) comprising a sulfur-containing boroester compound having the general formula (I):
wherein R
1
represents a hydrocarbyl group having from 4 to 12 carbon atoms, R
2
and R
3
independently represent —(OR
4
)
n
SR
1
or —(OR
4
)
n
SR
1
OH; R
4
represents a hydrocarbyl group having from 1 to 6 carbon atoms; n is an integer of from 1 to 4; and l and m are independently 0, 1 or 2;
a cyclic metaborate ester having the general formula (II):
wherein n, R
1
and R
4
, are defined as in formula (I); or a mixture of a borate ester of formula (I) and a metaborate ester of formula (II), and (B) a metal detergent.
A fourth aspect of the present invention is a method of making a marine diesel engine lubricant composition comprising blending a major amount of oil of lubricating viscosity and a minor amount of an additive as defined in the third aspect of the present invention.
A fifth aspect of the present invention is a method of reducing the piston ring and cylinder liner wear of a marine diesel engine, the method comprising lubricating the engine with a lubricant composition according to the first or third aspects of this invention, or made by the method according to the second or fourth aspects of this invention.
A sixth aspect of the present invention is the use of a lubricant composition to reduce the piston ring and cylinder liner wear of a marine diesel engine which comprises lubricating the engine with a lubricant composition according to the first, or third aspects of this invention, or made by the method according to the second or fourth aspects of this invention.
A seventh aspect of the present invention is a method of lubricating a marine diesel engine which comprises supplying to the engine a marine diesel engine lubricant composition according to the first or third aspects of the invention, or made by the method according to the second or fourth aspects of the invention. In performing the seventh aspect of the invention, the engine may be supplied with a fuel having a sulfur-content, expressed as elemental sulfur, of not greater than 1.5, such as 0.5 to 1, mass %.
In this specification, TBN (Total Base Number) is as measured by ASTM D2896, and viscosity index is as defined by ASTM D2270.
In this specification, unless otherwise stated, proportions of additives are quoted in terms of the proportion of active ingredient thereof, sometimes referred to as “a.i.”, e.g. such proportions do not include diluent.
In this specification, by “hydrocarbyl” is meant a group that is connected to the remainder of the molecular via a carbon atom, that contains hydrogen and carbon atoms, and that may contain atoms other than hydrogen and carbon, such as hetero atoms, provided they do not interfere with the essentially hydrocarbon nature of the group.
The features of the invention will now be discussed in more detail.
Marine Diesel Engines
The lubricant composition of the present invention may be suitable for use in a 4-stroke trunk piston diesel engine such as having an engine speed of 200-2,000, e.g. 400-1,000, rpm, and a brake horse-power (BHP) per cylinder of 50-3,000, preferably 100-2,000. It may also be suitable for use in a 2-stroke cross-head diesel engine such as having a speed of 40-200, preferably 60-120 rpm and a BHP
Infineum USA L.P.
Johnson Jerry D.
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