Estolide composition and process for making estolides

A method for preparing a composition of estolides that comprises reacting at least one unsaturated compound selected from among unsaturated fatty acids containing from 10 to 20 carbon atoms;

• with at least one saturated fatty acid containing from 4 to 18 carbon atoms;
• in the presence of at least one catalyst comprising at least one sulphonic acid functional group;
• the said method including no vacuum distillation step thereby making it possible to separate the monoestolides from the polyestolides,
• wherein the estolide composition has an iodine number less than or equal to 13 g/100 g of iodine,
• the composition of estolides comprising, relative to the total weight of the estolides:
• from 65 to 99.9% by weight of monoestolide(s) in the form of acid and/or ester;
• and
• from 0.1 to 35% by weight of polyestolide(s) in the form of acid and/or ester,
• wherein at least 50% by weight of the polyestolide(s) in the form of acid and/or ester have an estolide number EN equal to 2, EN being equal to 1 for the monoestolides and EN being greater than 1 for the polyestolides.