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
1999-10-13
2001-04-10
McAvoy, Ellen M. (Department: 1764)
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...
C508S221000, C508S287000
Reexamination Certificate
active
06214775
ABSTRACT:
The present invention relates to haze-free post-treated succinimides, their preparation, and their uses.
BACKGROUND OF THE INVENTION
Lubricating oil compositions for internal combustion engines generally contain a variety of additives to reduce or control deposits, wear, corrosion, etc. The present invention is concerned with compositions useful as dispersants in lubricating oil compositions.
In lubricating oils, dispersants function to control sludge, carbon, and varnish produced primarily by the incomplete combustion of the fuel, or impurities in the fuel, or impurities in the base oil used in the lubricating oil composition. Dispersants also control viscosity increase due to the presence of soot in diesel engine lubricating oils.
One of the most effective classes of lubricating oil dispersants is polyalkylene succinimides. In some cases, the succinimides have also been found to provide fluid-modifying properties, or a so-called viscosity index credit, in lubricating oil compositions. It produces a reduction in the amount of viscosity index improver that would otherwise have to be used.
Polyalkylene succinimides are generally prepared by the reaction of the corresponding polyalkylene succinic anhydride with a polyalkyl polyamine. Polyalkylene succinic anhydrides are generally prepared by a number of well-known processes. For example, there is a well-known thermal process (see, e.g., U.S. Pat. No. 3,361,673), an equally well-known chlorination process (see, e.g., U.S. Pat. No. 3,172,892), a combination of the thermal and chlorination processes (see, e.g., U.S. Pat. No. 3,912,764), and free radical processes (see, e.g., U.S. Pat. Nos. 5,286,799 and 5,319,030). Such compositions include one-to-one monomeric adducts (see, e.g., U.S. Pat. Nos. 3,219,666 and 3,381,022), as well as “multiply adducted” products, adducts having alkenyl-derived substituents adducted with at least 1.3 succinic groups per alkenyl-derived substituent (see, e.g., U.S. Pat. No. 4,234,435).
U.S. Pat. Nos. 3,361,673 and 3,018,250 describe the reaction of an alkenyl- or alkyl-substituted succinic anhydride with a polyamine to form alkenyl or alkyl succinimide lubricating oil dispersants and/or detergent additives.
U.S. Pat. No. 4,612,132 teaches that alkenyl or alkyl succinimides may be modified by reaction with a cyclic or linear carbonate or chloroformate such that one or more of the nitrogens of the polyamine moiety is substituted with a hydrocarbyl oxycarbonyl, a hydroxyhydrocarbyl oxycarbonyl, or a hydroxy poly(oxyalkylene) oxycarbonyl. These modified succinimides are described as exhibiting improved dispersancy and/or detergency in lubricating oils.
U.S. Pat. No. 4,747,965 discloses modified succinimides similar to those disclosed in U.S. Pat. No.4,612,132, except that the modified succinimides are described as being derived from succinimides having an average of greater than 1.0 succinic groups per long chain alkenyl substituent.
U.S. Pat. No. 4,234,435 teaches a polyalkene-derived substituent group with a number average molecular weight (M
n
) in the range of 1500 to 3200. For polybutenes, an especially preferred M
n
range is 1700 to 2400.
U.S. Pat. No. 5,112,507 discloses a polymeric ladder type polymeric succinimide dispersant in which each side of the ladder is a long chain alkyl or alkenyl, generally having at least about 30 carbon atoms, preferably at least about 50 carbon atoms. The dispersant is described as having improved hydrolytic stability and shear stress stability, produced by the reaction of certain maleic anhydride-olefin copolymers with certain polyamines. The patent further teaches that the polymer may be post-treated with a variety of post-treatments, and describes procedures for post-treating the polymer with cyclic carbonates, linear mono- or polycarbonates.
U.S. Pat. Nos. 5,334,321 and 5,356,552 disclose certain cyclic carbonate post-treated alkenyl or alkylsuccinimides having improved fluorocarbon elastomer compatibility, which are preferably prepared by the reaction of the corresponding substituted succinic anhydride with a polyamine having at least four nitrogen atoms per mole.
U.S. Pat. No. 5,716,912 discloses polyalkylene succinimides prepared by reacting, under reactive conditions, a mixture of a polybutene succinic acid derivative, an unsaturated acidic reagent copolymer of an unsaturated acidic reagent and an olefin, and a polyamine, then treating those succinimides with cyclic carbonates, linear mono- or polycarbonates or a boron compound.
SUMMARY OF THE INVENTION
The present invention provides a post-treated succinimide that is haze-free. One of the problems with post-treating succinimides with carbonates is that a haze is often formed. This haze problem is more pronounced when the succinimide is formed from reaction mixtures having an amine to total anhydride charge mole ratio (A/TA CMR) of greater than 0.5:1, yet such a higher A/TA CMR is desirable to get higher nitrogen levels and higher TBN.
This haze problem is also more pronounced when the cyclic carbonate to basic nitrogen charge mole ratio (EC/BN CMR) is greater than 1:1, yet such higher EC/BN CMR is desirable to get improved deposit control.
Our haze-free post-treated succinimide is prepared by a two-step process. In the first step, an alkenyl or alkyl succinimide is treated with an oil-soluble, strong acid. In the second step, the treated succinimide is contacted with a cyclic carbonate to post-treat the succinimide. The combination of time, temperature, and acid concentration of the first step and the time and temperature of the second step are adjusted to form the post-treated succinimide haze-free.
Preferably, the succinimide is a polybutene succinimide derived from polybutenes having a number average molecular weight of from 500 to 5000, more preferably from 2000 to 2400. In one embodiment, the succinimide is prepared by reacting under reactive conditions a mixture of a polybutene succinic acid derivative, an unsaturated acidic reagent copolymer of an unsaturated acidic reagent and an olefin, and a polyamine.
Preferably, the oil-soluble, strong acid is an oil-soluble, strong organic acid, more preferably a sulfonic acid. Preferably, the sulfonic acid is an alkyl aryl sulfonic acid. Most preferably, it is an alkyl benzene sulfonic acid wherein the alkyl group has from 4 to 30 carbon atoms. Preferably, the amount of sulfonic acid in the first step is from 0.1% to 10% based on the total weight of succinimide. When the cyclic carbonate to basic nitrogen charge mole ratio is higher than 1:1, or when the amine/total anhydride charge mole ratio is higher than 0.5:1, more sulfonic acid is needed to get satisfactory haze than when these charge mole ratios are lower. Usually a time from 1 to 20 hours and a temperature of from room temperature to 200° C. are sufficient for this step.
Preferably, the cyclic carbonate is either ethylene carbonate or propylene carbonate. Preferably, the carbonation step (b) is conducted at temperatures of from 0° C. to 250° C. Preferably, the molar charge of the cyclic carbonate to the basic nitrogen of the treated succinimide is from 0.2:1 to 10:1, more preferably from 0.5:1 to 5:1, still more preferably from 1:1 to 3:1, and most preferably approximately 2:1.
The haze-free post-treated succinimide can be used in a lubricating oil formulation comprising:
(a) a major amount of a base oil of lubricating viscosity,
(b) from 1% to 20% of haze-free post-treated succinimide,
(c) from 0% to 30% of at least one detergent,
(d) from 0% to 5% of at least one zinc dithiophosphate,
(e) from 0% to 10% of at least one oxidation inhibitor,
(f) from 0% to 1% of at least one foam inhibitor, and
(g) from 0% to 20% of at least one viscosity index improver.
For instance, the lubricating oil composition could be prepared blending together:
(a) a major amount of a base oil of lubricating viscosity,
(b) from 1% to 20% of haze-free post-treated succinimide,
(c) from 0% to 30% of at least one detergent,
(d) from 0% to 5% of at least one zinc dithiophosphate,
(e) from 0% to 10% of at least one oxidation inhibit
Chevron Chemical Company LLC
McAvoy Ellen M.
Sheridan Richard J.
Stumpf Walter L.
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