Process for preparing SiC-Bonded polyethersiloxanes

1. A process for preparing SiC-bonded polyethersiloxanes by precious metal-catalysed addition of olefinically unsaturated polyethers onto siloxanes having SiH groups, wherein

(i) prior to commencement of reaction, the siloxane having SiH groups is mixed together with a polyethersiloxane, and then

(ii) in a second step, this preliminary mixture is contacted with an olefinically unsaturated polyether and with a precious metal catalyst and optionally further additives,

and the SiC bond formation reaction is conducted up to an SiH conversion, determined by gas-volumetric means, of at least 97%.

2. The process according to claim 1 , wherein the polyethersiloxane to be mixed with the siloxane having SiH groups corresponds in structural terms to that polyethersiloxane that originates from the SiC bond-forming addition of the olefinically unsaturated polyether onto the siloxane having SiH groups.

3. The process according to claim 1 , wherein the polyethersiloxane to be mixed with the siloxane having SiH groups is added in amounts of 5 to 100 percent by mass, based on the mass of the siloxane having SiH groups plus the mass of the olefinically unsaturated polyether.

4. The process according claim 1 , wherein the at least one siloxane bearing SiH groups which is used for SiC bond formation conforms to one of the formulae (I) to (V):

with R 1 , identically or differently: alkyl and/or aralkyl and/or aromatic radical, each comprising 1 to 10 carbon atoms,

and with 1≤n≤250,

with R 1 , identically or differently: alkyl and/or aralkyl and/or aromatic radical, each comprising 1 to 10 carbon atoms,

and with a, identically or differently: 1≤a≤60 and

with 0<b≤10,

with R 1 , identically or differently: alkyl and/or aralkyl and/or aromatic radical, each comprising 1 to 10 carbon atoms

with 0≤x≤250 and

with 1≤y≤50,

with R 1 , identically or differently: alkyl and/or aralkyl and/or aromatic radical, each comprising 1 to 10 carbon atoms,

with 0≤x≤250 and

1≤y≤50,

with R 1 , identically or differently: alkyl and/or aralkyl and/or aromatic radical, each comprising 1 to 10 carbon atoms,

and with 4≤(k+1)≤5 and

1≥1.

5. The process according to claim 4 , wherein the R 1 radical is a methyl group.

6. The process according to claim 1 , wherein the olefinically unsaturated polyether conforms to the formula (VI):

A[-O—(CH 2 —CHR—O—) m —(CH 2 —CH 2 —O—) n —(CH 2 —CH(CH 3 )—O—) o —Z] a   (VI)

with A an olefinically unsaturated organic radical having at least two carbon atoms, of an organic starter compound for provision of the polyether and

R independently a saturated alkyl group having 2-18 carbon atoms or an aromatic radical,

and

Z either hydrogen,

a linear or branched, saturated or unsaturated hydrocarbyl radical having 1-18 carbon atoms, or

m 0 up to 50,

n 0 up to 250,

o 0 up to 250,

a 1 up to 8,

wherein the sum total of m, n and o is not less than 1.

7. The process according to claim 1 , wherein it is conducted in the presence of a precious metal catalyst selected from the group consisting of platinum complexes, rhodium complexes, osmium complexes, ruthenium complexes, palladium complexes, iridium complexes or the derivatives thereof that have been immobilized on support materials including silica, alumina or activated carbon, and solutions thereof.

8. The process according to claim 1 , wherein it is conducted in the presence of a precious metal catalyst selected from complexes of zero-valent platinum and/or solutions thereof.

9. The process according to claim 1 , wherein the amount of the precious metal catalyst used is 1 to 100 ppm by weight, based on the mass of the siloxane having SiH groups plus the mass of the olefinically unsaturated polyether.

10. The process according to claim 1 , wherein the precious metal-catalysed addition of the olefinically unsaturated polyethers onto siloxanes having SiH groups is undertaken at temperatures between 0° C. and 200° C.

11. The process according to claim 1 , wherein the siloxane having SiH groups is mixed together with a polyethersiloxane by stirring, and the preliminary mixture is contacted with an olefinically unsaturated polyether and with a precious metal catalyst and optionally further additives by further stirring.

12. The process according to claim 1 , wherein the amount of the precious metal catalyst used is 2 to 10 ppm by weight, based on the mass of the siloxane having SiH groups plus the mass of the olefinically unsaturated polyether.

13. The process according to claim 1 , wherein the precious metal-catalysed addition of the olefinically unsaturated polyethers onto siloxanes having SiH groups is undertaken at temperatures between 50° C. and 140° C.

14. The process according to claim 6 , wherein the A in formula (VI) is

an olefinically unsaturated organic radical having at least three carbon atoms, and

R is an ethyl group or a phenyl radical, Z is selected from the group consisting of methyl, ethyl, propyl, butyl, vinyl, allyl or methallyl group, and

m is from 0 to 30,

n is from 3 to 220,

o is from 3 to 220, and

a is from 1 to 6.

15. The process according to claim 6 , wherein the

Z is the radical of an organic acid of the formula —C(═O)—Z E where Z E is an organic radical, and

m is from 0 to 20,

n is from 5 to 200,

o is from 5 to 200, and

a is from 1 to 4.

16. The process according to claim 6 , wherein Z E is a linear or branched, saturated or unsaturated hydrocarbyl radical having 1-17 carbon atoms.

17. The process according to claim 6 , wherein Z E is selected from the group consisting of methyl group, or an aromatic hydrocarbyl radical having 6 to 20 carbon atoms.

18. The process according to claim 6 , wherein Z E is a phenyl radical

a linear or branched, saturated or unsaturated hydrocarbyl radical having 1-18 carbon atoms.

19. The process according to claim 6 , wherein Z E is a radical of the formula —C(═O)—O—Z C where Z C is an organic radical.

20. The process according to claim 6 , wherein Z E is a radical of the formula —C(═O)—O—Z C where Z C is a phenyl radical.