Process for producing polyoxyalkylene polysiloxane block polymers

1. A process for producing a SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymer, the process comprising:

reacting an end-equilibrated α,ω-diacetoxypolydimethylsiloxane with a mixture comprising at least one polyether polyol and at least one polyether monool or at least one monohydric alcohol,

wherein the SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymer is represented by formula (I)

C—B-(AB) a —C1   (I)

in which

A=a polyoxyalkylene block of the general formula (C n H 2n O) b —,

B=a polysiloxane block of the general formula (SiR 2 O) c —,

C, C1=identical or different alkoxypolyoxyalkylene radicals of general formula (II)

Z—O—[CH 2 —CH(R 1 )O] d —  (II)

where Z=an alkyl, alkylene, aryl or alkylaryl radical,

or

C, C1=an alkyl radical with the proviso that C or C1 possesses an alkoxypolyoxyalkylene radical of general formula (II) where Z=hydrogen,

or

C, C1=identical or different alkoxypolyoxyalkylene radicals of general formula (II) where Z=a hydrogen with the proviso that C or C1 possesses an alkoxypolyoxyalkylene radical of general formula (II) where Z=an alkyl, alkylene, aryl or alkylaryl radical,

R=identical or different C 1-4 -alkyl radicals or phenyl radicals with the proviso that at least 90% of the radicals R are methyl radicals,

R 1 =identical or different hydrogen radicals, C 1-12 -alkyl radicals or phenyl radicals,

a=1 to 20,

b=an average value of from 10 to 130,

c=3 to 100,

d=independently of one another in C/C1 values of from 2 to 20 with the proviso that the average value is in the range from 2 to <15, and

n=2 to 12 with an average numerical value of from 2.7 to 4.0.

2. The process according to claim 1 , wherein the end-equilibrated α,ω-diacetoxypolydimethylsiloxane is of formula (III)

wherein

R 2 is an alkyl radical having 1 to 4 carbon atoms or a phenyl radical, and

x=2≤x≤250.

3. The process according to claim 2 , wherein the end-equilibrated, α,ω-diacetoxypolydimethylsiloxane of formula (III) is obtainable from a reaction of

a silane and/or siloxane bearing an alkoxy group, and/or

a silane and/or siloxane bearing a hydroxy group, and/or

a simple siloxane cycle and/or DT cycle,

with acetic anhydride, superacid, and acetic acid.

4. The process according to claim 2 , wherein, for a production of the end-equilibrated α,ω-diacetoxypolydimethylsiloxane of formula (III), a silane and/or siloxane bearing an alkoxy group and containing at least one T and/or Q group, and/or DT cycle are used.

5. The process according to claim 1 , wherein, for A of formula (I), a polyether polyol, selected from the group consisting of polyether dials, polyether polyols, and a mixture thereof, is used.

6. The process according to claim 1 , wherein, for C, C1 of formula (I), a polyether monool or a monohydric C 1 -C 18 alcohol, selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, isobutanol, and a mixture thereof, is used.

7. The process according to claim 1 , wherein a molar ratio of the end-equilibrated α,ω-diacetoxypolydimethylsiloxane to the mixture is in a range from 1.01 to 3.00.

8. The process according to claim 1 , wherein the reacting is conducted at temperatures of 20° C. to 180° C.

9. process according to claim 1 , wherein a base to be used in the reaction is selected from the group consisting of alkali metal, alkaline earth metal carbonates, hydrogen carbonates, amines, and a combination thereof.

10. The process according to claim 1 , wherein an inert solvent used in the reaction is selected from the group consisting of alkanes, cycloalkanes, alkyl aromatics, end-capped polyethers, emollient esters, and a combination thereof.

11. The process according to claim 1 , wherein the reacting is effected solventlessly.

12. The process according to claim 1 , wherein a weight-average molecular weight of the polysiloxane block (B) is between 650 to 6,500 g/mol.

13. The process according to claim 1 , wherein the SiOC-linked, linear polydimethylsiloxane-polyoxyalkylene block copolymer has a weight-average molecular weight of at least 2,000 g/mol to approx. 160,000 g/mol.

14. The process according to claim 1 , wherein the mixture comprises at least one polyether diol, and at least one polyether monool or at least one monohydric alcohol.

15. The process according to claim 2 , wherein

more than 90% of R 2 are methyl radicals, and

x=10≤x≤30.

16. process according to claim 3 , wherein superacid is trifluoromethanesulfonic acid.