Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Compound of indeterminate structure – prepared by reacting a...
Reexamination Certificate
1998-12-29
2001-02-13
Medley, Margaret (Department: 1714)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Compound of indeterminate structure, prepared by reacting a...
C508S543000, C525S279000, C525S281000, C525S282000, C525S283000, C525S293000, C525S296000, C525S309000, C525S315000
Reexamination Certificate
active
06187721
ABSTRACT:
This application is a 371 of PCT/GB97/01556 dated Jun. 10, 1997.
The present invention concerns a lubricant for use in diesel engines, including passenger car and heavy duty commercial diesel engines.
Diesel engines produce soot as a by-product of the combustion process. The soot increases the viscosity of lubricants used in the diesel engines and eventually the lubricants become too thick to be workable. The soot therefore reduces the working life of the lubricants, and money and time are wasted in early replacement of the unworkable lubricant. The soot also causes wear of the diesel engines, which reduces their working life.
Lubricants currently on the market for diesel engines typically comprise: 65-80% by weight of base oil; 5-15% by weight of viscosity index improver(s) (VII); and 10-22% by weight of a detergent inhibitor (DI) package. The viscosity index improver(s) (VII) may be a non-dispersant viscosity index improver (NDVII) and/or a dispersant viscosity index improver (DVII). One function of the detergent inhibitor (DI) package is to provide a dispersant to disperse the soot and thereby prevent soot related viscosity increase of the lubricant and wear on the engine. The choice and amount of viscosity index improver(s) (VII) used in the lubricant, e.g. whether it is a NDVII or a DVII, will affect the choice and amount of dispersant, which is provided by the detergent inhibitor package (DI), present in the lubricant. In conventional formulations, the choice and amount of DI package is normally chosen to provide approximately at least:
a) 6% dispersant(s) in the finished lubricant when using a non-dispersant viscosity index improving agent (NDVII); or
b) 4% dispersant(s) in the finished lubricant when using a traditional dispersant viscosity index improving agent (DVII), such as those available prior to approximately 1994.
Although it is possible to increase the amount of soot that is dispersed by a lubricant by increasing the amount of dispersant, which is provided by the detergent inhibitor (DI) package, present in the lubricant, increasing the amount of dispersant can cause the following negative effects: it can increase the wear on the engine by interfering with the anti-wear additives in the formulation; it can cause damage to seals in contact with the lubricant; it negatively impacts low temperature viscometrics; and it can increase the cost of the lubricant.
The inventors of the present invention are therefore concerned with the problem of increasing the amount of soot that is dispersed by a lubricant without increasing the amount of dispersant, which is normally provided by the detergent inhibitor (DI) package, present in the finished lubricant. The inventors are also concerned with the problem of controlling soot related viscosity increase with lower levels of dispersant, which is normally provided by the DI package, than conventionally used by those skilled in the art.
In accordance with the present invention there is provided use of a lubricant in a diesel engine to disperse soot produced by the diesel engine, the soot being dispersed without adversely affecting the viscosity of the lubricant; the lubricant comprising a dispersant and a functionalized viscosity index improver; the functionalized viscosity index improver comprising a highly functionalized graft copolymer reaction product of an oxygen, a nitrogen, or an oxygen and a nitrogen containing, ethylenically unsaturated, aliphatic or aromatic monomer having from 2 to about 50 carbon atoms grafted on to a polyolefin copolymer.
In accordance with the present invention there is also provided a method of controlling viscosity changes of a lubricant in a diesel engine that are caused by build-up of soot, the method comprising using the lubricant defined above as the lubricant in the diesel engine.
The inventors have found a lubricant that allows an increased amount of soot to be dispersed without increasing the amount of dispersant, which is normally provided by the detergent inhibitor (DI), present in the lubricant.
The inventors have also found a highly functionalized graft copolymer, which, when incorporated into a lubricant, allows the lubricant to disperse soot produced as a by-product of a diesel engine without adversely affecting the viscosity of the lubricant.
The inventors have also found that lower than conventional amounts (e.g. 4% or less) of dispersant, which is normally provided by the DI package, may be used in combination with the highly functionalized graft copolymer defined above to control soot related viscosity increase.
The inventors have also found that the lubricants of the present invention can comprise lower than conventional amounts (e.g. 4% or less) of dispersant, which is normally provided by the detergent inhibitor (DI), and still meet the current industry soot handling tests for passenger car and heavy duty commercial diesel engines.
By ‘adversely affecting the viscosity of the lubricant’, we mean increasing the viscosity of the lubricant to an unacceptable level, for example, a level defined in a standard industry test such as the Mack T8 Test.
Highly functionalized graft copolymers suitable for use in the present invention may be prepared using either a solution grafting process or a melt grafting process.
Preferred solution graft copolymers suitable for use in the present invention are disclosed in WO 96/12746, which was published on May 2nd 1996. The whole contents of WO 96/12746 are expressly incorporated into this patent application by reference thereto.
Other suitable graft copolymers may be prepared by grafting maleic anhydride on to the polyolefin copolymer and reacting the resulting succinic anhydride with an appropriate nitrogen containing moiety such as polyamine. Polyolefins grafted to the appropriate level may be prepared by following the practices disclosed in, for example, U.S. Pat. No. 144,181; U.S. Pat. No. 4,507,515; U.S. Pat. No. 4,557,847; U.S. Pat. No. 4,632,769; U.S. Pat. No. 4,693,838; U.S. Pat. No. 4,707,285; and U.S. Pat. No. 5,350,532. Suitable solution graft copolymers may be comprised of Mannich Base condensates.
WO 96/12746, the whole contents of which are hereby incorporated by reference thereto, discloses the reaction materials and reaction conditions that are needed to produce a preferred graft copolymer for use in the present invention. In particular, this document discloses the reaction materials and the reaction conditions that are needed to produce the graft copolymer reaction product and the viscosity index improving agent which can be used in the preferred lubricant of the present invention.
WO 96/12746, the whole contents of which are hereby incorporated by reference thereto, discloses: examples of preferred polyolefins that are suitable for use as a backbone for grafting; preferred graftable monomers that are suitable for being grafted on to the polyolefin backbone; and preferred initiators, solvents and inhibitors that are suitable for the grafting reaction.
WO 96/12746, the whole contents of which are hereby incorporated by reference thereto, also discloses suitable melt reaction conditions for producing the preferred grafted polyolefin by a melt reaction process.
WO 96/12746, the whole contents of which are hereby incorporated by reference thereto, also discloses test methods for determining: the proportions of nitrogen on the grafted copolymer and the process fluid (assuming the reaction is carried out in a process solvent); the amount of residual unreacted graftable monomer in a graft copolymer; the dispersancy of the graft copolymer; the UV/RI ratio; and the aromatic content of solvent or process fluid used in the solution grafting reactions.
WO 96/12746, the whole contents of which are hereby incorporated by reference thereto, also discloses details of the preferred: base oils; graft copolymers; non-grafted polyolefins; other dispersants; detergents; anti-wear agents; anti-oxidants; pour point depressants; and minor ingredients.
A preferred melt grafted copolymer for use in the present invention is PARATONE 8500, available from E
Ainscough Niall
Brown Myron
Carlisle Danny
Goldblatt Irwin
Henderson Kenneth
Castrol Limited
Medley Margaret
Nixon & Vanderhye P.C.
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