Method for preparing fatty acid esters of natural origin functionalized by oxidation for use as fluxing oils for bitumen

A method for preparing a fluxing oil based on fatty substances having a natural origin and having been chemically functionalized by oxidation, including the steps of:

• i) providing a fatty substance or a mixture of fatty substances of natural origin comprising at least one compound selected from triglycerides, diglycerides and monoglycerides,
• ii) subjecting said fatty substance or mixture of fatty substances of natural origin to at least one transesterification reaction with at least one alkanol,
• iii) subjecting the compound or mixture of compounds obtained at step ii) to at least one chemical functionalization reaction by oxidation, and
• iv) collecting the fluxing oil,
• wherein said chemical functionalization introduces at least one functional group selected from carboxylic acid, epoxy, peroxide, aldehyde, ether, ester, alcohol and ketone groups, the fluxing oil collected at step iv) has an iodine number ranging from 50 to 200, and said fatty substance(s) of natural origin comprise(s) carbon-carbon double bonds, at least 15% of which are oxidized during step iii).