This application is directed to multifunctional additives which improve the low temperature properties of distillate fuels and to fuel compositions containing minor amounts thereof.
Traditionally, the low-temperature properties of distillate fuels have been improved by the addition of kerosene, sometimes in very large amounts (5-70 wt %). The kerosene dilutes the wax in the fuel, i.e. lowers the overall weight fraction of wax, and thereby lowers the cloud point, filterability temperature, and pour point simultaneously. The additives of this invention effectively lower both the cloud point and CFPP (Cold Filter Plugging Point) of distillate fuel without any appreciable dilution of the wax component of the fuel.
Other additives known in the art have been used in lieu of kerosene to improve the low-temperature properties of distillate fuels. Many such additives are polymeric materials with pendant fatty hydrocarbon groups. These additives are limited in the range of their activity, however; most improve fuel properties by lowering the pour point and/or filterability temperature. These additives have little or no effect on the cloud point of the fuel.
No art is known to applicants which teaches or suggest the additive products and compositions of this invention. However, U.S. Pat. Nos. 3,910,987 and 3,910,981 disclose the use of certain aminodiols in the preparation of petroleum additives.
The additives of this invention are substantially different, however, both in terms of structure and function. They are oligomeric and/or polymeric materials obtained via condensation reactions, e.g. the reaction of diaminodiols with acids and/or anhydrides. In terms of activity, these additives effectively lower distillate fuel cloud point, thus providing improved low-temperature fuel properties, and offering a unique and useful advantage over known distillate fuel additives.
These new additives are especially effective in lowering the cloud point of distillate fuels, and thus improve the low-temperature flow properties of such fuels without the use of any light hydrocarbon diluent, such as kerosene. In addition, the filterability properties are improved as demonstrated by lower CFPP temperatures. Thus, the additives of this invention demonstrate multifunctional activity in distillate fuels.