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The following examples are present to illustrate the invention but it is not to be considered as limited thereto. In the examples and throughout the specification, parts are by weight unless otherwise indicated.
EXAMPLE 1
In this example polyalkenyl succinic anhydride is heated to 170° C. and 1 molar equivalent of maleic anhydride is added slowly to the succinic anhydride over a period of 2 hours. After the addition is complete, the reaction mixture is then stirred for 3 hours without additional processing. This reaction produces the polyalkenyl disuccinic anhydride.
EXAMPLE 2
The polyalkenyl succinic anhydride starting material used in Example 1 is heated to 170° C. and 2 equivalents of maleic anhydride are added slowly over a period of 3 hours. After the addition is complete, the reaction mixture is stirred for 12 hours. This produces the polyalkenyl trisuccinic anydride or the derivative which contains three anhydride groups.
EXAMPLE 3
Polyalkenyl succinic anhydride containing a single anhydride group is heated to 120° C. in combination with a catalytic amount of lithium acetate. Thereafter, a polyethoxylated alcohol is added in an amount of 3 equivalents of alcohol per equivalent of succinic anhydride. After addition of the alcohol, the reaction mixture is stirred for 5 hours until the total acid number is reduced to below 10 milligrams of KOH per gram of compound, which is obtained by titration with potassium hydroxide.
EXAMPLE 4
In this example the dianhydride produced from Example 1 is heated to 120° C. in combination with a catalytic amount of lithium acetate. Thereafter 3 equivalents per anhydride of polyethoxylated alcohol is added to the reaction mixture and stirring is continued for 5 hours until the total acid number is reduced to below 10 milligrams of KOH per gram of compound.
EXAMPLE 5
Polyalkenyl trisuccinic anhydride produced in Example 2 was heated to 120° C. in combination with a catalytic amount of lithium acetate. Thereafter, 3 equivalents per anhydride of a polyethoxylated alcohol is added to the mixture and stirred for 5 hours until the total acid number was reduced to below 10 milligrams of KOH per gram of compound.
EXAMPLE 6
The dispersants described as being produced in Examples 3, 4 and 5 were then formulated as aqueous based hydraulic fluids. The aqueous based hydraulic fluid contained the following formulation wherein the dispersant is the reaction product of Examples 3, 4 or 5:
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