Polyglycerol esters and their use

1. A polyglycerol partial ester having the structure of Formula (I)

wherein R 1 , R 2 and R 3 , independent from each other, equal or different, are selected from the group consisting of:

—OH,

—OR 4 , where R 4 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

—OR 5 , where R 5 is a radical having the structure of Formula (I) wherein one of R 1 , R 2 and R 3 being a direct bond to the oxygen of —OR 5

wherein each molecule of the polyglycerol partial ester comprises at least one of each —OR 4 and —OR 5 , 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 n i , is the degree of polymerization of a single oligomer i, <n>is an average degree of polymerization of a polyglycerol mixture, and x i , is a proportion of the single oligomer i in the polyglycerol mixture.

2. The polyglycerol partial ester according to claim 1 wherein at least 1% of the polyglycerol obtained by hydrolysis or alcoholysis of the polyglycerol partial ester comprises cyclic structures.

3. The polyglycerol partial ester according to claim 1 , wherein the polyglycerol partial ester comprises an HLB-value from 2 to 10.

4. The polyglycerol partial ester according to claim 1 , wherein said polyglycerol partial ester has a melting point of at least 25° C.

5. 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 HOR 4 , with R 4 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 R 1 , R 2 and R 3 , independent from each other, equal or different, are selected from the group consisting of:

—OH, —OR 4 , where R 4 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

—OR 5 , where R 5 is a radical having the structure of Formula (I) wherein one of R 1 , R 2 and R 3 being a direct bond to the oxygen of —OR 5

wherein each molecule of the polyglycerol partial ester comprises at least one of each —OR 4 and —OR 5 , 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 n i , is the degree of polymerization of a single oligomer i, <n>is an average degree of polymerization of a polyglycerol mixture, and x i , is a proportion of the single oligomer i in the polyglycerol mixture.

6. A polyglycerol partial ester concentrate wherein a solvent is present consisting of

A) at least 50 wt. % of at least one polyglycerol partial esters according to claim 1 ,

B) up to 50 wt. % of a solvent and optionally

C) 0.1 wt. % to 5 wt. % of a preservative,

wherein the wt. % refer to the total weight of the concentrate and the wt. % of all components sum up to 100 wt. %.