Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic -co- compound
Patent
1996-10-03
1998-02-10
McAvoy, Ellen M.
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic -co- compound
508468, 44393, C10M14510, C10L 118
Patent
active
057169152
DESCRIPTION:
BRIEF SUMMARY
This invention concerns oil compositions having improved low temperature properties, and additives imparting such properties to hydrocarbon oils.
The general problem of decreased hydrocarbon oil flowability at low temperatures is well recognised in the art. Hydrocarbon oils typically contain normal alkanes which precipitate from the bulk oil at and below oil cloud point temperature, forming wax crystals. These wax crystals modify the flow characteristics of the hydrocarbon oil, eventually forming a spongy mass which entraps the bulk oil.
One well-recognised solution to this problem is the use of chemical additives to improve the flowability of hydrocarbon oil at temperatures below cloud point. This improvement may result from additive interaction with the forming wax crystals, for example by reducing crystal size, the smaller wax crystals appearing less likely to clog fine filters. Other additives inhibit wax crystallisation into platelets, instead causing the adoption of acicular crystal habits which pass through the filter pores more readily. Many such low temperature flow improving additives have been described in the art.
However, such additives commonly exhibit the problem of having non-universal application across the range of hydrocarbon oil types. Typically, a particular additive will prove effective only in oils sharing certain physical characteristics, and will prove largely ineffective in other oils. It is a continual challenge to devise additives effective in a range of oils, and particularly in those oils hitherto regarded in the art as difficult to treat with conventional low-temperature flow improving additives.
Comb polymers generally have one or more long chain substituents pendant from a polymer backbone, said substituents being bonded either directly to the backbone or indirectly to the backbone via interposed atoms or groups. Comb polymers are discussed in "Comb-like Polymers, Structure and Properties" by N. A. Plate and V. P. Shibaev, published in J. Poly. Sci, Macromolecular Revs. 8, p. 117 to 253 (1974). A number of classes of comb polymer useful as low temperature flow improving additives have been described in the art.
UK Patent No. 1,469,016 describes comb polymers derived from C.sub.6 to C.sub.18 alkyl esters of unsaturated C.sub.4 to C.sub.8 dicarboxylic acids, with copolymers of di-n-alkyl fumarates and vinyl acetate being preferred. Such comb polymers are shown to be effective as low temperature flow improvers only in fuel oils having high end points, i.e. final boiling points above 700.degree. F. (371.degree. C.).
European Patent Application No. 0,282,342 describes comb polymers derived from a C.sub.2 to C.sub.17 alpha-olefin or aromatic substituted olefin, and a mono- or di- C.sub.8 to C.sub.23 alkyl ester of certain unsaturated carboxylic acids. Such polymers are shown to be effective as low temperature flow improvers only in fuel oils having a relatively high final boiling point of above 360.degree. C.
UK Patent No. 2,023,645 describes a three component additive combination for fuel oils, in which "Component B" is a comb polymer having hydrocarbyl substituents in the form of straight chain alkyl groups of 6 to 30 carbon atoms. Such additive combinations are shown to be effective as low temperature flow improvers and as inhibitors of wax settling only in fuels having final boiling points of at least 361.degree. C.
The known comb polymers hereinbefore described have not proved substantially advantageous in hydrocarbon oils lacking the physical characteristic of high final boiling point.
WO 94/00386 discloses oil soluble ethylene polymers having, in addition to units derived from ethylene, units of the formulas R.sup.2 independently represents a group of the formula COOR.sup.3 or OOCR.sup.4, wherein R.sup.3 and R.sup.4 independently represent hydrocarbyl groups of, most preferably, at most 8 carbon atoms. Specifically-disclosed examples include ethylene vinyl n-octanoate (Example G) and ethylene vinyl n-heptanoate (Example F).
U.S. Pat. No. 4,863,486 discloses a class of comb
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Brown Gerald Ivan
Davies Brian William
More Lain
Tack Robert Dryden
Towe Derek A.
Exxon Chemical Patents Inc.
Mahon John J.
McAvoy Ellen M.
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