Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Heterocyclic ring compound; a heterocyclic ring is one...
Patent
1997-04-03
1999-08-03
McAvoy, Ellen M.
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Heterocyclic ring compound; a heterocyclic ring is one...
508293, 508551, 508554, C10M14900
Patent
active
059325259
DESCRIPTION:
BRIEF SUMMARY
This invention relates to multigrade lubricating oils for use in lubricating internal combustion engines, that contain basestocks with low levels of saturated hydrocarbons, and specifically to such oils which also comprise a multifunctional viscosity modifier.
Multigrade lubricating oils typically are identified by designations such as SAE 10W-30, 5W-30 etc. The first number in the multigrade designation is associated with a maximum low temperature (e.g.,-20.degree. C.) viscosity requirement for that multigrade oil as measured typically by a cold cranking simulator (CCS) under high shear rates (ASTM D5293, which is a revision of ASTM D2602), while the second number in the multigrade designation is associated with a high temperature viscosity requirement usually measured in terms of the kinematic viscosity (kV) at 100.degree. C. (ASTM D445). Thus, each particular multigrade oil must simultaneously meet both strict low and high temperature viscosity requirements, set e.g. by SAE specifications such as SAE J300, in order to qualify for a given multigrade oil designation.
The high temperature viscosity requirement is intended to prevent the oil from thinning out too much during engine operation which can lead to excessive wear and oil consumption. The maximum low temperature viscosity requirement is intended to facilitate engine starting in cold weather and to ensure pumpability, i.e., the cold oil should readily flow to the oil pump, otherwise the engine can be damaged due to insufficient lubrication.
The viscosity characteristic of a basestock on which a lubricating oil is based is typically expressed by the neutral number of the oil (e.g., S150N) with a higher neutral number being associated with a higher viscosity at a given temperature. Blending basestocks is one way of modifying the viscosity properties of the resulting lubricating oil. Unfortunately, merely blending basestocks of different viscosity characteristics may not enable the formulator to meet the low and high temperature viscosity requirements of some multigrade oils. The formulator's primary tool for achieving this goal is an additive conventionally referred to as a viscosity modifier (VM) or viscosity index improver (V.I. improver).
A monofunctional VM is conventionally an oil-soluble long chain polymer. A multifunctional VM (or alternately MFVM) is an oil soluble polymer which has been chemically modified e.g., functionalized and derivatized, to impart dispersancy as well as viscosity modification.
The basestocks which are typically used in lubricating oils may be synthetic or natural oils. Mineral oils contain various amounts of saturated hydrocarbons, such as straight or branched chain paraffins and naphthenes, and unsaturated hydrocarbons particularly aromatic hydrocarbons. Lubricating oils have traditionally used basestocks containing high levels of saturated hydrocarbon--also referred to as high saturate basestocks--since aromatic hydrocarbons give rise to difficulties in formulating for adequate performance in internal combustion engines. This has been known for some time, being discussed, for example, in "Lubricants for Fluid Film and Hertzian Contact Conditions", T. I. Fowle, Proc. Instn. Mech. Engrs. 1967-8, Vol 182, Pt 3A, pages 568-576, especially pages 568/9 and 571/2. More recently, "Chemistry and Technology of Lubricants", edited by R. M. Mortier and S. T. Orszulik, Blackie Academic and Professional, 1992, in chapter 1, "Base oils from Petroleum" R. J. Prince, pages 1-31, discusses the instability of aromatic components to oxidation which is still perceived as a problem. "Compositional Analysis of Re-refined and Non-Conventional Lubricant Base Oils: Correlations to Sequence VE and IIIE Gasoline Engine Tests", Stipanovic et aL, SAE Technical Paper Series, 941978, Oct. 17-20 1994 provides a statistical analysis in those engine tests which indicates a strong negative impact of various aromatic hydrocarbon types. Among other consequences it is generally accepted that there is a tendency for unsaturated components and particularly
REFERENCES:
patent: 4234435 (1980-11-01), Meinhardt et al.
patent: 5427702 (1995-06-01), Chung et al.
Ney Johan
Robson Robert
Russell Trevor
Exxon Chemical Patents Inc.
McAvoy Ellen M.
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