Process for purification of polyether carbonate polyols
View Patent ↗This invention relates to a process for the production of a high purity polyether carbonate polyol. The high purity polyether carbonate polyols prepared by the process herein contain a low level of catalyst residues. The process adds diatomaceous earth to a polyether carbonate polyol to form a suspension, mixes the suspension for a specified time period at a specified temperature, and filters the suspension to form the high purity polyether carbonate polyol.
1. A process for producing a high purity polyether carbonate polyol which contains no more than 90 ppm of catalyst residue, consisting of
(1) adding from 0.5% to 5% by weight, based on 100% by weight of polyether carbonate polyol, of diatomaceous earth having a permeability rating of less than or equal to 0.200 darcys to a polyether carbonate polyol to form a suspension;
(2) mixing the suspension, formed in (1) for a time period of from 30 minutes to 5 hours at temperature in the range of from 20° C. to 150° C.;
and
(3) filtering the suspension from (2), thereby forming the high purity polyether carbonate polyol.
2. The process of claim 1 , which comprises (1) adding from 0.75% to 2.0% by weight, based on 100% by weight of polyether carbonate polyol, of diatomaceous earth to the polyether carbonate polyol.
3. The process of claim 1 , which comprises (1) adding from 1.00 to 1.75% by weight, based on 100% by weight of polyether carbonate polyol, of diatomaceous earth to the polyether carbonate polyol.
4. The process of claim 1 , wherein said diatomaceous earth has a permeability rating of from 0.01 to 0.200 darcys.
5. The process of claim 1 , wherein said diatomaceous earth has a permeability rating of from 0.02 to 0.150 darcys.
6. The process of claim 1 , which comprises (2) mixing said suspension formed in (1) for a time period of from 60 minutes to 240 minutes.
7. The process of claim 1 , which comprises (2) mixing said suspension formed in (1) for a time period of from 60 to 90 minutes.
8. The process of claim 1 , which comprises (2) mixing said suspension formed in (1) at a temperature in the range of from 70 to 125° C.
9. The process of claim 1 , which comprises (2) mixing said suspension formed in (1) at a temperature in the range of from 75 to 120° C.
10. The process of claim wherein said diatomaceous earth is selected from the group consisting of non-calcined diatomaceous earth, calcined diatomaceous earth, flux calcined diatomaceous earth and acid washed diatomaceous earth.
11. The process of claim 1 , wherein said polyether carbonate polyol is prepared with a double metal cyanide catalyst.
12. The process of claim 1 , wherein said high purity polyether carbonate polyol contains no more than 9 ppm of cobalt residue.