Fuel and related compositions – Liquid fuels – Solid hydrocarbon polymer containing
Reexamination Certificate
1997-12-31
2004-07-27
McAvoy, Ellen M. (Department: 1764)
Fuel and related compositions
Liquid fuels
Solid hydrocarbon polymer containing
C044S389000, C044S393000, C044S412000, C044S425000, C044S443000
Reexamination Certificate
active
06767374
ABSTRACT:
This invention relates to oil compositions, primarily to fuel oil compositions, and more especially to fuel oil compositions susceptible to wax formation at low temperatures, to additives for use in such fuel oil compositions, and to the use of the additives to improve the cold flow properties of fuels.
Fuel oils, whether derived from petroleum or from vegetable sources, contain components, e.g., alkanes, that at low temperature tend to precipitate as large crystals or spherulites of wax in such a way as to form a gel structure which causes the fuel to lose its ability to flow. The lowest temperature at which the fuel will still flow is known as the pour point.
As the temperature of the fuel falls and approaches the pour point, difficulties arise in transporting the fuel through lines and pumps. Further, the wax crystals tend to plug fuel lines, screens, and filters at temperatures above the pour point. These problems are well recognized in the art, and various additives have been proposed, many of which are in commercial use, for depressing the pour point of fuel oils. Similarly, other additives have been proposed and are in commercial use for reducing the size and changing the shape of the wax crystals that do form. Smaller size crystals are desirable since they are less likely to clog a filter. The wax from a diesel fuel, which is primarily an alkane wax, crystallizes as platelets; certain additives inhibit this and cause the wax to adopt an acicular habit, the resulting needles being more likely to pass through a filter, or forms a porous cake, than are platelets. The additives may also have the effect of retaining in suspension in the fuel the crystals that have formed, the resulting reduced settling also assisting in prevention of blockages.
Effective wax crystal modification (as measured by cold filter plugging point (CFPP) and other operability tests as well as simulated and field performance) may be achieved by flow improvers, for example, by ethylene vinyl acetate (EVAC) or propionate copolymers.
In a first aspect the present invention provides the use, to improve cold flow characteristics of a fuel oil, of an additive composition comprising an oil-soluble hydrogenated block diene polymer, comprising at least one crystallizable block, obtainable by end-to-end polymerization of a linear diene, and at least one non-crystallizable block, the non-crystallizable block being obtainable by 1,2-configuration polymerization of a linear diene, by polymerization of a branched diene, or by a mixture of such polymerizations.
More especially, the invention provides the use, to improve cold flow characteristics of a fuel oil, of an additive composition additionally comprising a cold flow improver other than the hydrogenerated block polymer defined above.
Preferably, the other cold flow improver is selected from
(A) ethylene-unsaturated ester compounds,
(B) comb polymers,
(C) polar nitrogen compounds,
(D) compounds comprising a ring system having at least two substituents comprising a linear or branched aliphatic hydrocarbylene group optionally interrupted by one or more hetero atoms and carrying a secondary amino group, the substituents on the amino groups each being a hydrocarbyl group containing 9 to 40 carbons,
(E) hydrocarbon polymers, and
(F) polyoxyalkylene compounds,
the components A to F being other than the hydrogenerated block polymer. The presence of one or more of these other cold flow improvers leads to unexpected enhancements of wax crystal modification additional to those obtained with the block polymer alone.
As used in this specification the term “hydrocarbon . . . ” and related terms refer to a group having a hydrocarbon or predominantly hydrocarbon character. Among these, there may be mentioned hydrocarbon groups, including aliphatic, (e.g., alkyl), alicyclic (e.g., cycloalkyl), aromatic, aliphatic and alicyclic-substituted aromatic, and aromatic-substituted aliphatic and alicyclic groups. Aliphatic groups are advantageously saturated. These groups may contain non-hydrocarbon substituents provided their presence does not alter the predominantly hydrocarbon character of the group. Examples include keto, halo, hydroxy, nitro, cyano, alkoxy and acyl. The groups may also or alternatively contain atoms other than carbon in a chain or ring otherwise composed of carbon atoms.
In a second aspect, the present invention provides an additive composition comprising
(i) an oil-soluble hydrogenated block diene polymer, comprising at least one crystallizable block, obtainable by end-to-end polymerization of a linear diene, and at least one non-crystallizable block, the non-crystallizable block being obtainable by 1,2-configuration polymerization of a linear diene, by polymerization of a branched diene, or by a mixture of such polymerizations, and
(ii) a cold flow improver selected from
(A) ethylene-unsaturated ester compounds,
(B) comb polymers,
(C) polar nitrogen compounds,
(D) compounds comprising a ring system having at least two substituents comprising a linear or branched aliphatic hydrocarbylene group optionally interrupted by one or more hetero atoms and carrying a secondary amino group, the substituents on the amino groups each being a hydrocarbyl group containing 9 to 40 carbons,
(E) hydrocarbon polymers, and
(F) polyoxyalkylene compounds,
the components A to F being other than a component as defined in (i).
In a third aspect, the present invention further provides a fuel oil composition comprising a major proportion of a fuel oil and a minor proportion of an additive composition comprising;
(i) an oil-soluble hydrogenated block diene polymer, comprising at least one crystallizable block, obtainable by end-to-end polymerization of a linear diene, and at least one non-crystallizable block, the non-crystallizable block being obtainable by 1,2-configuration polymerization of a linear diene, by polymerization of a branched diene, or by a mixture of such polymerizations, and
(ii) a cold flow improver other than one as defined in (i).
More especially, in the fuel oil composition aspect, component (ii) of the additive composition is a cold flow improver as defined under (A) to (F) above.
In a forth aspect, the present invention still further provides an additive concentrate comprising a fuel oil and a minor proportion of the additive composition comprising
(i) an oil-soluble hydrogenated block diene polymer, comprising at least one crystallizable block, obtainable by end-to-end polymerization of a linear diene, and at least one non-crystallizable block, the non-crystallizable block being obtainable by 1,2-configuration polymerization of a linear diene, by polymerization of a branched diene, or by a mixture of such polymerizations, and
(ii) a cold flow improver other than one as defined in (i).
The invention still further provides an additive concentrate comprising a solvent miscible with fuel oil and a minor proportion of an additive composition as defined in the second aspect of the invention.
In British Specification No. 1490563, there is disclosed the use of a hydrogenated homopolymer of butadiene or a copolymer of butadiene with a C
5
to C
8
diene as a cold flow improver for fuels. The copolymer is produced by polymerizing, e.g., a butadiene-isopropene mixture. GB-A-2087425 describes the use of a reaction product of a cyclic anhydride with an N-alkyl polyamine combined with, inter alia, a hydrogenated butadieneisoprene copolymer.
WO 92/16567, describes hydrogenated block copolymers of butadiene and, inter alia, isoprene, and oleaginous compositions containing them, the disclosure of which is incorporated herein by reference. Their use is predominantly as viscosity index improvers in lubricating oils, but there are also references to use in fuels.
WO 92/16568, describes hydrogenated block polymers containing 1,4-butadiene and 1,2-butadiene addition products, the disclosure of which is incorporated herein by reference. Their uses are said to be similar to those of the polymers of WO 92/16567.
In the present invention, hydrogenated block polymers are used, preferably in c
Fetters Lewis John
Goberdhan Dhanesh Gordon
Huang John
Lewtas Kenneth
McAleer Andrew Matthew
Exxon Chemical Patents Inc.
McAvoy Ellen M.
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