Fuel and related compositions – Liquid fuels – Organic oxygen compound containing
Reexamination Certificate
1997-04-02
2004-11-23
McAvoy, Ellen M. (Department: 1764)
Fuel and related compositions
Liquid fuels
Organic oxygen compound containing
C568S606000, C568S608000, C568S622000, C568S625000, C568S658000, C568S678000, C568S679000
Reexamination Certificate
active
06821308
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to polyoxyalkylene monoethers. In particular, the invention relates to polyoxyalkylene monoethers with reduced water affinity that have value as components of fuel additive detergent systems.
BACKGROUND OF THE INVENTION
Polyoxyalkylene monoethers and their derivatives are well known and are widely used as components of fuel additive detergent systems to maintain the cleanliness of intake systems in internal combustion engines. Many traditional detergent systems have two components: (1) a polyoxyalkylene component, which acts as a carrier; and (2) a detergent. A wide variety of detergents are known, including carbamates, succinates, amine polyethers, and polyisobutylene amines (PIB amines). Examples of such two-component systems are those shown in U.S. Pat. Nos. 5,298,039 and 4,877,416. More recently, one-component detergent systems that incorporate a polyoxyalkylene moiety and a detergent function into a single polymer backbone have surfaced (see, for example, U.S. Pat. Nos. 5,427,591 and 5,600,025).
Polyoxyalkylene monoethers used as fuel additives must be oleophilic to be compatible with gasolines and the lipophilic detergents used to discourage or eliminate deposit formation. To achieve good solubility in and compatibility with fuels, polyoxyalkylene components are typically terminated with C
4
-C
60
(more preferably C
9
-C
30
) hydrocarbyl (alkyl, aryl, or aralkyl) groups as described, for example, in U.S. Pat. Nos. 5,298,039, 4,877,416, and 4,422,856. Even with the hydrocarbyl groups present, the polyoxyalkylene components can be hydrophilic enough to form emulsions on contact with water in the fuel, or to phase separate from other hydrocarbon components.
To enhance oil-solubility of polyoxyalkylene monoethers, formulators increase the oleophilic nature of the initiator alcohol (see, e.g., U.S. Pat. Nos. 5,298,039 and 5,600,025) or incorporate relatively hydrophobic oxyalkylene units such as those derived from C
4
epoxides (see, e.g., U.S. Pat. No. 5,004,478) or branched C
11
-C
14
epoxides (see, e.g., U.S. Pat. No. 4,274,837). Unfortunately, these modifications are often more costly than desirable.
Polyoxyalkylene monoethers normally contain relatively minor amounts of polyoxyalkylene diol impurities. These diol impurities result from base-catalyzed polymerization of alkylene oxides, e.g., propylene oxide, in the presence of water, which acts as a starter for the polymerization. The diols lack the hydrocarbyl moiety of the monoethers. Until now, these minor amounts of diol impurities were not believed to adversely affect the performance of polyoxyalkylene monoethers in fuels.
Polyoxyalkylene monoethers made with C
3
and higher alkylene oxides contain a second type of impurity: alkoxylated unsaturates. A side reaction complicates base-catalyzed polymerization of many alkylene oxides: some of the alkylene oxide isomerizes to an allylic alcohol and other unsaturates under the reaction conditions. For example, propylene oxide isomerizes to allyl alcohol under basic conditions. Reaction of the allylic alcohol with the alkylene oxide gives alkoxylated unsaturates. While these impurities are “monoethers,” they lack a relatively hydrophobic end group. Until now, these alkoxylated unsaturates, usually propoxylated allyl alcohols, were not believed to adversely affect the performance of polyoxyalkylene monoethers in fuels.
SUMMARY OF THE INVENTION
The invention is an oleophilic polyoxyalkylene monoether. The monoether has the structure:
Z—(A)
n
—OH
wherein A is an oxyalkylene group, Z is a hydrocarbyl residue selected from the group consisting of C
4
-C
60
alkyl, aryl, and aralkyl, and n, which is the average number of oxyalkylene groups, is within the range of about 2 to about 500. The monoether contains less than about 6 mole percent of alkoxylated unsaturates, and preferably less than about 5 mole percent of polyoxyalkylene diols.
We surprisingly found that polyoxyalkylene monoethers containing less than about 6 mole percent of alkoxylated unsaturates offer substantial advantages for fuels. In particular, the monoethers have reduced water affinity and a substantially reduced tendency to form emulsions with water present in lipophilic systems. These advantages of the monoethers suggest better fuel solubility. We also surprisingly found that reducing the content of polyoxyalkylene diol impurities in the monoethers to less than about 5 mole percent offers similar advantages. By using deposit-control additives based on polyoxyalkylene monoethers of the invention, fuel formulators can offer better solutions for cleaner engines.
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Combs George
McDaniel Kenneth G.
Bayer Antwerp N.V.
Gil Joseph C.
McAvoy Ellen M.
Mrozinski, Jr. John E.
Whalen Lyndanne M.
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