Polyglycerol esters and their use

A method for the preparation of polyglycerol partial esters comprising the process of esterification of:

• a) a polyglycerol mixture comprising an average degree of polymerization of from 2 to 8 with
• b) at least one monocarboxylic acid comprising a carboxylic acid HOR4, with R4 a linear, unsubstituted acyl radical with a chain length of from 16 to 22 carbon atoms
• with the proviso that the at least one carboxylic acid bears an iodine value of smaller than 50, said polyglycerol partial esters having the structure of Formula (I)
• wherein R1, R2 and R3, independent from each other, equal or different, are selected from the group consisting of:
• —OH, —OR4, where R4 is a linear, unsubstituted acyl radical with a chain length of from 16 to 22 carbon atoms with the proviso that the monocarboxylic acids obtained from the acyl radical by saponification bears an iodine value of smaller than 50, and
• —OR5, where R5 is a radical having the structure of Formula (I) wherein one of R1, R2 and R3 being a direct bond to the oxygen of —OR5
• wherein each molecule of the polyglycerol partial ester comprises at least one of each —OR4 and —OR5, with the provisos that the polyglycerol obtained by hydrolysis or alcoholysis of the polyglycerol partial ester comprises an average degree of polymerization of from 2 to 8 and the polydispersity index of said polyglycerol is greater than 0.75,
• wherein said polydispersity index is calculated as
• ∑
• i
• ⁢
• ⁢
• 
• n
• i
• -
• 〈
• n
• 〉
• 
• ·
• x
• i
• ,
• where ni, is the degree of polymerization of a single oligomer i, <n>is an average degree of polymerization of a polyglycerol mixture, and xi, is a proportion of the single oligomer i in the polyglycerol mixture.