Fuel and related compositions – Liquid fuels – Containing organic -c
Reexamination Certificate
2000-07-18
2001-08-21
Medley, Margaret (Department: 1714)
Fuel and related compositions
Liquid fuels
Containing organic -c
C044S408000
Reexamination Certificate
active
06277158
ABSTRACT:
This invention relates to an additive concentrate for use in fuels, especially in gasolines for internal combustion engines.
It is well-known that the performance of gasolines and other fuels can be improved through the use of additive technology. For example, detergents can be added to inhibit the formation of intake system deposits, thereby improving engine cleanliness. More recently it has been suggested that friction modifiers may be added to gasolines to increase fuel economy by reducing engine friction. In selecting suitable components for a detergent/friction modifier additive package it is important to ensure a balance of properties. The friction modifier should not adversely affect the deposit control of the detergent. In addition the package should not exhibit any harmful effects on the performance of the engine, such as valve sticking.
Current practice in the supply of gasoline is generally to pre-mix the fuel additives into a concentrate in a hydrocarbon solvent base, and then to inject the concentrate into gasoline pipelines used to fill tankers prior to delivery to the customer. Under present operating conditions, the maximum amount of concentrate that can be incorporated into a tanker of gasoline is typically about 2000 ppm based on the weight of the gasoline, of which about 700-1500 ppm is taken up by a conventional detergent-containing gasoline additive package. To facilitate injection of the concentrate into the gasoline, it is important that the concentrate is in the form of a low viscosity, homogeneous liquid. Problems have been encountered in achieving a stable concentrate due to the poor solubility of conventional friction modifiers, especially at low temperatures. The solubility of the friction modifier may be assisted by employing solubilising agents. However, the amount of solubilising agent required to solubilise the desired level of friction modifier in the concentrate often exceeds the maximum amount possible given the constraints on the amount of concentrate that can be injected into the gasoline, and the amount of solubilising agent that can be contained in the concentrate. In addition, some solubilising agents tend to react adversely with the friction modifier, or other additives contained in the concentrate, causing chemical degradation and/or a reduction in performance in the resulting gasoline composition.
Accordingly, there is a need for a detergent/friction modifier additive concentrate for gasoline that provides both deposit control and friction reduction, which is stable over the temperature range at which the concentrate may feasibly be stored, and which does not adversely affect the performance and properties of the finished gasoline or engine in which the gasoline is used.
The present invention provides an additive concentrate comprising by weight based on the total weight of the concentrate:
(a) 0.2 to 10% ashless friction modifier which is a liquid at room temperature and pressure selected from (i) n-butylamine oleate or derivatives thereof, (ii) a substance comprising tall oil fatty acid or derivatives thereof, and (iii) a mixture of (i) and (ii),
(b) 10 to 80% deposit inhibitor, and
(c) 10 to 80% carrier fluid.
The particular selection of friction modifier (a) enables a stable additive concentrate to be formulated within the current constraints of a maximum of approximately 2000 ppm by weight concentrate in the finished gasoline, of which up to about 1500 ppm is deposit inhibitor, whilst containing sufficient friction modifier to achieve a significant benefit in friction loss and hence an improvement in fuel economy, and without the need for additional solubilising agent for the friction modifier.
Solubilising agents, for example hydrocarbon solvents such as alcohols, may be included if desired, and therefore are not excluded from the scope of the present invention, but they are not an essential requirement.
The friction modifier is preferably a liquid over the temperature range at which the additive concentrate is likely to be stored. Typically this temperature range is from −20 to +35° C.
The friction modifier may be n-butylamine oleate or a derivative thereof, a substance comprising tall oil fatty acids or derivatives thereof or a mixture of these. Despite substantial research investigating a wide range of available friction modifier compounds, it has been found that only these two compound types provide the benefits explained above.
n-Butylamine oleate has the formula:
An example of a suitable commercially available n-butylamine oleate friction modifier is RS 124 supplied by Bitrez Ltd.
The substance comprising tall oil fatty acids may either be 100% tall oil fatty acids, or substantially 100% tall oil fatty acids, or may be a mixture of tall oil fatty acids and other fatty acids or derivatives thereof Preferably such a mixture contains at least 50 wt %, more preferably at least 70 wt %, tall oil fatty acids. An example of a suitable commercially available substance containing tall oil fatty acids is Tolad 9103 supplied by Petrolite Ltd.
The amount of friction modifier contained in the additive concentrate is from 0.2 to 10 wt %, preferably from 0.5 to 5 wt %, and more preferably from 1 to 4 wt %. On the basis of a total concentrate treat level in the finished gasoline of 2000 ppm by weight, this corresponds to a treat level of friction modifier in the finished gasoline of from 4 to 200 ppm, preferably 10 to 100 ppm, more preferably 20 to 60 ppm.
The deposit inhibitor (b) may be any suitable commercially available additive. Deposit inhibitors for gasoline, usually referred to as detergents or dispersants, are well known and a variety of compounds can be used. Examples include polyalkylene amines, and polyalkylene succinimides where the polyalkylene group typically has a number average molecular weight of from 600 to 2000, preferably from 800 to 1400, and polyether amines. A preferred detergent for the additive concentrate of the present invention is a polyalkylene amine, for example polyisobutylene amine. Examples of suitable PIB-amines are given in U.S. Pat. No. 4,832,702, the disclosure of which is incorporated herein by reference. Also, PIB-amine detergents can be obtained from, for example from Exxon Chemical Company, Oronite and BASF.
The amount of deposit inhibitor contained in the additive concentrate is from 10 to 80 wt %, preferably from 20 to 75 wt %, and more preferably from 30 to 60 wt %. Based on a total treat level of the additive concentrate of 2000 ppm by weight, this corresponds to a treat level of deposit inhibitor in the finished gasoline of from 50 to 1500 ppm, preferably 100 to 1000 ppm, more preferably 200 to 800 ppm.
The carrier fluid may be any suitable carrier fluid that is compatible with the gasoline and is capable of dissolving or dispersing the components of the additive package. Typically it is a hydrocarbon fluid, for example a petroleum or synthetic lubricating oil basestock including mineral oil, synthetic oils such as polyesters or polyethers or other polyols, or hydrocracked or hydroisomerised basestock. Alternatively the carrier fluid may be a distillate boiling in the gasoline range. The amount of carrier fluid contained in the additive concentrate of the invention is from 10 to 80 wt %, preferably from 20 to 75 wt %,and more preferably from 30 to 60 wt %.
The additive concentrate according to the invention may also contain a demulsifier to inhibit the formation of emulsion in the gasoline which can form if the gasoline becomes contaminated with water. A demulsifier is particularly advantageous if the friction modifier is the substance comprising tall oil fatty acids as the acids tend to promote any emulsification. Demulsifiers for gasoline are well known and examples of suitable compounds are alkoxylated phenol formaldehyde resins. If a demulsifier is employed in the additive concentrate it is preferably in an amount from 1 to 4 ppm by weight based on the weight of the gasoline.
The additive concentrate is preferably incorporated into the gasoline or other fuel by injection, alt
Allocca Joseph J.
DiToomer Cephia
Exxon Research and Engineering Company
Medley Margaret
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