Decolorization of polyols
Natural oil-based polyols that are high in color, e.g., >40 APHA, are decolorized when exposed to high frequency visible light and/or low frequency UV light, with or without the combination of heat and/or air exposure.
1. A process for decolorizing a natural oil-based polyol, the process comprising the step of exposing the polyol to actinic radiation of a wavelength of 250 to 550 nanometers.
2. The process of claim 1 in which the polyol is exposed to the actinic radiation at a temperature between ambient and 120 ° C.
3. The process of claim 2 in which the polyol is simultaneously contacted with an oxygen source.
4. The process of claim 1 in which the polyol is derived from a vegetable oil.
5. The process of claim 4 in which the vegetable oil is subjected to transesterification followed by hydroformylation and then hydrogenation to form hydroxymethylated fatty acid methyl esters.
6. The process of claim 5 in which the hydroxymethylated fatty acid methyl esters are polymerized to form the polyol.
7. The process of claim 6 in which the hydroxymethylated fatty acid methyl esters are catalytically polymerized.
8. The process of claim 7 in which the catalyst is stannous octoate.
9. The process of claim 8 in which residual polymerization catalyst is deactivated simultaneously with the decolorization of the polyol.