Polyether polyols, process for preparing polyether polyols and their use for producing polyurethanes
The present invention relates to a process for preparing polyether polyols, in which at least one hydroxyl-comprising fatty acid ester and/or at least one hydroxyl-modified fatty acid ester is reacted with the aid of a double metal cyanide catalyst in at least two process sections with in each case a mixture of ethylene oxide and at least one further alkylene oxide different from ethylene oxide.
1. A process for preparing a polyether polyol, the process comprising:
reacting
a hydroxyl-comprising fatty acid ester, a hydroxyl-modified fatty acid ester, or any mixture thereof,
with
a mixture of ethylene oxide and a further alkylene oxide different from ethylene oxide in the presence of a double metal cyanide catalyst in at least two process sections,
wherein
each process section in the at least two process sections is a phase of the process where composition of the mixture of ethylene oxide and a further alkylene oxide different from ethylene oxide remains constant for a period of at least thirty minutes, and
the mixture in each process section has a composition different from the mixture in an immediate preceding and an immediate subsequent process section.
2. The process according to claim 1 , wherein
the hydroxyl-comprising fatty acid ester is at least one selected from the group consisting of a hydroxyl-comprising fat and a hydroxyl-comprising oil, and
the hydroxyl-modified fatty acid ester is at least one selected from the group consisting of a hydroxyl-modified fat and a hydroxyl-modified oil.
3. The process according to claim 1 , wherein the further alkylene oxide is at least one selected from the group consisting of propylene oxide, 1,2-butylene oxide, and 2,3-butylene oxide.
4. The process according to claim 1 , wherein the process comprises precisely two process sections.
5. The process according to claim 1 , wherein the mixture comprises precisely one further alkylene oxide different from ethylene oxide.
6. The process according to claim 1 , wherein the further alkylene oxide is propylene oxide.
7. The process according to claim 1 , wherein a mass ratio of ethylene oxide to a total mass of all further alkylene oxides in the mixture in a last process section is from 35:65 to 75:25.
8. The process according to claim 1 , wherein a mass ratio of ethylene oxide to a total mass of all further alkylene oxides in the mixture in process sections preceding a last process section is from 35:65 to 1:99.
9. The process according to claim 1 , wherein a mass ratio of ethylene oxide to a total mass of all further alkylene oxides in the mixture in a last process section is from 40:60 to 70:30.
10. The process according to claim 1 , wherein a mass ratio of ethylene oxide to a total mass of all further alkylene oxides in the mixture in process sections preceding a last process section is from 30:70 to 5:95.
11. The process according to claim 1 , wherein the double metal cyanide catalyst is at least one selected from the group consisting of a Co—Zn double metal cyanide catalyst, a Fe—Zn double metal cyanide catalyst, and a Ni—Zn-based double metal cyanide catalyst.
12. The process according to claim 1 , wherein the double metal cyanide catalyst is a zinc hexacyanocobaltate catalyst.