Process for preparing polyoxyalkylene polyester polyols
The present invention relates to a process for preparing polyoxyalkylene polyester polyols by reacting a starter compound having Zerewitinoff-active H atoms, a cyclic dicarboxylic acid anhydride and a fatty acid ester with an alkylene oxide in the presence of a basic catalyst. The invention further relates to polyoxyalkylene polyester polyols resulting from the method and to a preparation method for polyurethanes by reaction of the polyoxyalkylene polyester polyols according to the invention.
1. A process for preparing a polyoxyalkylene polyester polyol by reaction of a starter compound (1) having Zerewitinoff-active H atoms, a cyclic dicarboxylic anhydride (2) and a fatty acid ester (3) with an alkylene oxide (4) in the presence of a basic catalyst (5) comprising:
(i) providing a mixture (i) comprising the starter compound (1) and the fatty acid ester (3), wherein the mixture (i) contains no cyclic dicarboxylic anhydride (2);
(ii) reacting the mixture (i) from step (i) with a portion (v1) of the alkylene oxide (4), wherein at least 0.15 mol of alkylene oxide (4) per 1 mol of Zerewitinoff-active hydrogen atoms of the starter compound (1) is added to form a compound (ii);
(iii) reacting the compound (ii) formed in step (ii) by addition of the dicarboxylic anhydride (2) to form a compound (iii); and
(iv) reacting the compound (iii) from step (iii) with a portion (v2) of the alkylene oxide (4), wherein at least 1.15 mol of alkylene oxide (4) per 1 mol of the dicarboxylic anhydride (2) is added.
2. The process as claimed in claim 1 , wherein the sum of the portion (v1) of the alkylene oxide (4) added in step (ii) and the portion (v2) of the alkylene oxide (4) added in step (iv) is at least 90 mol % of the total amount (vT) of the alkylene oxide (4) added.
3. The process as claimed in claim 1 , wherein the basic catalyst (5) is added in step (i) and/or in step (iii) and/or in step (iv).
4. The process as claimed in claim 1 , wherein the basic catalyst (5) comprises an amine.
5. The process as claimed in claim 4 , wherein the amine comprises an aromatic amine.
6. The process as claimed in claim 1 , wherein the alkylene oxide (4) comprises propylene oxide and/or ethylene oxide.
7. The process as claimed in claim 1 , wherein the fatty acid ester (3) is employed in an amount of 10% by weight to 70% by weight, based on the sum of all components.
8. The process as claimed in claim 1 , wherein the fatty acid ester (3) has no free hydroxyl groups in the fatty acid residues.
9. The process as claimed in 8 , wherein the fatty acid ester (3) comprises cottonseed oil, peanut oil, coconut oil, linseed oil, palm kernel oil, olive oil, corn oil, palm oil, jatropha oil, rapeseed oil, soybean oil, sunflower oil, herring oil, sardine oil, tallow, or a mixture thereof.
10. The process as claimed in claim 1 , wherein the cyclic dicarboxylic anhydride (2) comprises an aromatic cyclic dicarboxylic anhydride.
11. The process as claimed in claim 1 , wherein a mixing power input introduced is between 0.8 and 5 W/1, based on the liquid volume after termination of step (iv).
12. The process as claimed in claim 1 , wherein the polyoxyalkylene polyester polyol has an OH number of 100 to 300 mg KOH/g, determined according to the specification of DIN 53240.
13. The process as claimed in claim 1 , wherein the polyoxyalkylene polyester polyol has a Gardner color number of 2.0 to 8.0, determined according to ASTM D 4890-88 in which the sample is dissolved in dimethyl sulfoxide in a weight ratio of 1:2.
14. The process as claimed in claim 1 , further comprising reacting the polyoxyalkylene polyester polyol with a polyisocyanate to prepare a polyurethane.
15. The process as claimed in claim 2 , wherein the sum of the portion (v1) of the alkylene oxide (4) added in step (ii) and the portion (v2) of the alkylene oxide (4) added in step (iv) is 100% of the total amount (vT) of the alkylene oxide (4) added.
16. The process as claimed in claim 3 , wherein the basic catalyst (5) is added in step (i).
17. The process as claimed in claim 5 , wherein the aromatic amine comprises imidazole, 1-methylimidazole, 2-methylimidazole, 4(5)-methylimidazole, 2,4(5)-dimethylimidazole, 1-ethylimidazole, 2-ethylimidazole, 1-phenylimidazole, 2-phenylimidazole, 4(5)-phenylimidazole, N,N-dimethylaminopyridine, or a mixture thereof.
18. The process as claimed in claim 7 , wherein the fatty acid ester (3) is employed in an amount of 10% by weight to 40% by weight, based on the sum of all components.
19. The process as claimed in claim 18 , wherein the fatty acid ester (3) is employed in an amount of 10% by weight to 30% by weight, based on the sum of all components.