Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic -co- compound
Reexamination Certificate
2002-08-07
2004-06-08
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
C508S470000, C526S319000, C526S320000
Reexamination Certificate
active
06746993
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a viscosity index improver (hereinafter referred to as VII or VI improver). More particularly, it relates to a VII for lube oils, such as automatic transmission fluids (ATF), gear oils, hydraulic fluids and engine oils.
2. Description of the Prior Art
As VI improvers to improve viscosity index (hereinafter referred to as VI) of lube oils, there have been known heretofore copolymers of C
1-18
alkyl (meth)acrylates (for instance, U.S. Pat. No. 5,622,924).
The term “(meth)acrylate” represents acrylate and/or methacrylate and also “C
1-18
alkyl” represents alkyl group containing 1-18 carbon atoms; and similar expressions are used hereinafter.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a VII capable of imparting an improved VI to a lube oil.
It is another object of this invention to provide a VII capable of imparting an improved low temperature viscosity characteristics to a lube oil.
It is still another object of the invention to provide a VII having an improved shear stability.
It is yet another object of the present invention to provide a high VI lube oil having an improved shear stability.
It is further object of the present invention to provide an automotive lube oil capable of meeting fuel cost-saving requirement of an automobile.
It is still further object of the present invention to provide a monomer suitable for producing a VII.
Briefly, these and other objects of this invention as hereinafter will become more readily apparent have been attained broadly by a VII, comprising a polymer (A1) or (A0) as follows.
Polymer (A1) has a solubility parameter (hereinafter referred to as SP) of 8.6-9.4, a crystallizing initiation temperature (hereinafter referred to as Tc) of at most −15° C. and a steric hindrance factor F, defined by the following equation (1), within the range of 0-13.
F=
4
X+Y
(1)
In the equation (1), X and Y represent the total atom numbers at the 6th position and the 7th position, respectively, in the side chain(s), counted from the backbone.
Polymer (A1) comprises units of at least one monomer selected from the group consisting of the following monomers (a)-(d):
(a) C
1-40
alkyl group-containing (meth)acrylates,
(b) alkyl alkenyl ethers,
(c) alkenyl carboxylates, and
(d) nitrogen-containing unsaturated monomers.
Polymer (A0), used in another aspect of the invention, comprises units of at least one branched C
20-40
alkyl group-containing (meth)acrylate (a0) and units of at least one other alkyl (meth)acrylate. Said (meth)acrylate (a0) is capable of providing a homopolymer having a Tc of at most 5° C.
Polymers (A1) and (A0), hereinafter generically referred to as Polymers (A), have a weight-average molecular weight (hereinafter referred to as Mw) of usually 5,000-2,000,000.
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Ota Yoshihisa
Yuki Tsuyoshi
McAvoy Ellen M.
Sanyo Chemical Industries Ltd.
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