Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic -co- compound
Reexamination Certificate
2002-06-05
2003-11-18
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic -co- compound
C508S480000, C508S482000, C508S485000
Reexamination Certificate
active
06649576
ABSTRACT:
This invention relates to lubricating oil compositions such as multigrade lubricants that, in particular, give enhanced performance in diesel engine piston cleanliness and piston ring-sticking tests.
Lubricating oil compositions (or lubricants) for the crankcase of internal combustion engines are well-known and it is also well-known for them to contain additives (or additive components) to enhance their properties and performance.
Increasingly, the demands of original equipment manufacturers (OEM's) to meet performance criteria dictate the properties of lubricants. One such performance criterion concerns the sticking of piston rings during operation of a compression-ignited (diesel) internal combustion engine. This is usually referred to briefly as “ring-sticking”; it may be measured by the VWTDi test (CEC L-78-T-99). A second performance criterion that is measured in this test is piston cleanliness.
Other performance criteria of interest include the volatility of the lubricant, the fuel economy performance of the lubricant, and the chlorine content of the lubricant.
The various criteria clearly constrain formulators of lubricants in terms of additive components and amounts, and of basestocks, that may be used.
EP-A-1 087 008 describes a way of meeting “ring-sticking” test requirements by provision of certain additive components.
The present invention provides a different approach, i.e. by providing a specific basestock mixture in order to meet the above mentioned requirements.
In a first aspect, the invention is a crankcase lubricating oil composition, such as an SAE 5W-20, 5W-30 or 5W-40 composition, comprising, or made by admixing, a major amount of
(A) a basestock of lubricating viscosity comprising a Group III basestock, in a major amount, and a Group V basestock, in the form of an ester, in a minor amount, such as 3 to 5, preferably 3 to 10, mass % based on the mass of the composition, other than basestocks that arise from provision of additive components in the composition; and minor amounts of lubricant additive components comprising
(B) a dispersant, such as an ashless dispersant;
(C) a metal detergent;
(D) one or more other lubricant additive components selected from anti-oxidants, anti-wear agent and friction modifiers; and
(E) a viscosity modifier.
The data contained in the specification demonstrate that the use of the basestock mixture (A) unexpectedly improves the performance of lubricating oil compositions in the TDi test.
In a second aspect, the invention is a method of lubricating a compression-ignited internal combustion engine comprising operating the engine and lubricating the engine with a lubricating oil composition according to the first aspect of the invention.
In a third aspect, the invention is a method of reducing the ring-sticking tendencies of a compression-ignited internal combustion engine comprising adding to the engine a lubricating oil composition according to the first aspect of the invention.
In a fourth aspect, the invention is a combination comprising the crankcase of a compression-ignited engine and a lubricating oil composition according to the first aspect of the invention for lubricating the crankcase.
In this specification:
“comprising” or any cognate word is taken to specify the presence of stated features, integers, steps or components, but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof;
“major amount” means in excess of 50 mass % of the composition;
“minor amount” means less than 50 mass % of the composition both in respect of the stated additive and in respect of the total mass % of all of the additives present in the composition, reckoned as active ingredient of the additive or additives;
“oil-soluble” or “dispersible” used herein do not necessarily indicate that the compounds or additives are soluble, dissolvable, miscible, or capable of being suspended in the oil in all proportions. These do mean, however, that they are, for instance, soluble or stably dispersible in oil to an extent sufficient to exert their intended effect in the environment in which the oil is employed. Moreover, the additional incorporation of other additives may also permit incorporation of higher levels of a particular additive, if desired.
The invention also provides the product obtained or obtainable as a result of any reaction between the various additive components of the composition or concentrates, essential as well as customary and optimal, under the conditions of formulation, storage or use:
The features of the invention will now be discussed in more detail as follows:
Multigrade Lubricants
Multigrade lubricants perform over wide temperature ranges. Typically, they are identified by descriptors such as SAE 10W-30 or SAE 5W-30. The first number in the multigrade descriptor is associated with a safe cranking temperature (e.g., −20° C.) viscosity requirement for that multigrade oil as measured by a cold cranking simulator (CCS) under high shear rates (ASTM D5293). In general, lubricants that have low CCS viscosities allow the engine to crank more easily at lower temperatures and thus improve the ability of the engine to start at those ambient temperatures.
Multiviscosity—grade oils, commonly referred to as “multigrades” are designed to operate over wide temperature ranges and are identified by descriptors such as SAE 10W-30 or SAE 5W-30,. Their properties are defined in the Society of Automotive Engineers document SAE J300. This publication defines multigrades in terms of two criteria:
Maximum low temperature cranking and pumping viscosities and
Maximum and minimum kinematic viscosities at 100° C. and a minimum high-shear viscosity at 150° C. and 10
8
s
−1
.
Low temperature properties define which “W” grade shall be assigned to a lubricant and high temperature properties define the “non W” part of the designation.
SAE J300 defines a series of W grades with SAE 0W representing the requirements for operation at lowest temperatures. SAE 5W, 10W, 15W, 20W and 25W are also defined, these grades are suitable for progressively higher minimum temperature of operation.
Non-W grades are also assigned a numerical designation, these define a scale of increasing high temperature viscosity. This scale starts with SAE 20 and goes through SAE 30, 40 and 50 to the most viscous grade, SAE 60.
This system of viscometric classification of automotive crankcase lubricants finds universal application with the vehicle and lubricant manufacturing industries.
(A) Basestock
The basestock (sometimes referred to as “base oil”) is an oil of lubricating viscosity and is the primary liquid constituent of a lubricant into which additives and possibly other oils are blended to produce the final lubricant.
Basestocks may be categorised in Groups I to V according to the API Engine Oil Licensing and Certification System (EOLCS) API 1509 definitions, which definitions are used to define the basestocks of this invention. Thus:
a) Group I basestocks contain less than 90 percent saturates and/or greater than 0.03 percent sulfur and have a viscosity index greater than or equal to 80 and less than 120 using the test methods specified in Table E-1.
b) Group II basestocks contain greater than or equal to 90 percent saturates and less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 80 and less than 120 using the test methods specified in Table E-1.
c) Group III basestocks contain greater than or equal to 90 percent saturates and less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 120 using the test methods specified in Table E-1.
d) Group IV basestocks are polyalphaolefins (PAO).
e) Group V basestocks include all other basestocks not included in Group I, II, III, or IV.
As stated, the basestock (A) in the present invention comprises a major amount of a Group III basestock and a minor amount of Group V basestock in the form of an ester. Preferably, it consists essentially of such basestocks, but may contain minor amounts of G
Bell Ian A. W.
Robson Robert
Howard Jacqueline V.
Infineum International Inc.
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