Process for the production of polyether carbonate polyols

1. A process for the production of polyether carbonate polyols comprising adding one or more alkylene oxides and carbon dioxide to one or more H-functional starter substances in the presence of at least one DMC catalyst, wherein the adding step comprises

(i) suspending the DMC catalyst in one or more H-functional starter substances to form a suspension,

(ii) bringing the suspension from (i) into contact with one or more alkylene oxides and with 10 to 200 bar carbon dioxide to form a mixture, and

(iii) reacting the mixture resulting from (ii) in a tubular reactor at a temperature of 80 to 150° C.

2. The process according to claim 1 , wherein in step (iii) the reaction pressure is 10 to 200 bar.

3. The process according to claim 1 , wherein in step (ii)

(ii-1) the suspension from (i) is firstly brought into contact in a first mixer with one or more alkylene oxides and is then brought into contact in a second mixer with 10 to 200 bar carbon dioxide, or

(ii-2) the suspension from (i) is firstly brought into contact in a first mixer with 10 to 200 bar carbon dioxide and is then brought into contact in a second mixer with one or more alkylene oxides.

4. The process according to claim 1 , wherein step (iii) is carried out at a reaction pressure of 15 to 180 bar.

5. The process according to claim 1 , wherein step (iii) is carried out at a temperature of 90 to 135° C. and a reaction pressure of 20 to 180 bar.

6. The process according to claim 1 , wherein the tubular reactor is constructed from a continuous piece of tube.

7. The process according to claim 1 , wherein the internal diameter of the tubular reactor is from 1.1 mm to 500 mm.

8. The process according to claim 1 , wherein the tubular reactor is constructed from at least two tubes joined together.

9. The process according to claim 1 , wherein the tubular reactor is constructed from at least two tubes joined together, and wherein the tubular reactor over the first 20 to 60% of its length has an internal diameter of from 1.1 mm to <100 mm, and over the second 80 to 40% of its length has an internal diameter of from 100 mm to 500 mm.

10. The process according to claim 1 , wherein the tubular reactor is free from several layers arranged in parallel one on top of the other so that each layer has a plurality of channels arranged parallel to one another which form a continuous flow path from one side of the plate to the opposite side thereof.

11. The process according to claim 1 , wherein the tubular reactor is free from several layers arranged in parallel one on top of the other, which are microstructured so that each layer has a plurality of channels arranged parallel to one another which form a continuous flow path from one side of the plate to the opposite side thereof.

12. The process according to claim 1 , wherein the one or more H-functional starter substance is selected from the group consisting of polyether polyol, polyester polyol, polyether carbonate polyol, water, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,4-butanediol, 1,4-butenediol, 1,4-butynediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol; 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, 1,4-bis(hydroxymethyl)cyclohexane, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, dibutylene glycol trimethylolpropane, glycerol, tris(hydroxyethyl) isocyanurate, castor oil, pentaerythritol, sorbitol, hexitol, sucrose, starch, starch hydrolysate, cellulose, cellulose hydrolysate, hydroxyl-functionalised fats and hydroxyl-functionalised oils.

13. The process according to claim 1 , wherein the tubular reactor has a ratio of tube length L to tube diameter dR of L/dR>50.