Process for purifying brominated polystyrene
AssigneeGreat Lakes Chemical Corporation
InventorsNicolai A. Favstritsky, William R. Fielding, John L. Sands, Robert J. Stahl
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Abstract
The invention relates to a process for the purification of brominated styrenic homo-polymers and co-polymers. The purification process reduces or removes contained aliphatic bromine, and free bromine resulting from the reaction of the brominated reagent with the polystyrene backbone. In addition, the method optionally removes occluded inorganic halide impurities from the polymer. These impurities are considered undesirable due to their adverse effects on thermal aging and stability of the final end use resin formulations.
Claims19
A process for reducing the amount of impurities in styrenic homo-polymers or co-polymers that have been brominated, and having an organic bromine content of up to approximately 76 percent by weight, said polymers including as occluded impurities at least one of halogens in aliphatic positions on the polymer backbone and elemental halogen, said process comprising the steps of:
- a. combining said brominated polymers with an aqueous non-solvent to form a slurry;
- b. reacting the at least one of halogens in aliphatic positions on the polymer backbone and elemental halogen occluded impurities in said brominated polymers while in the slurry with a halogen-reducing agent for a sufficient time and at a sufficient temperature to reduce the at least one of aliphatic halogen compounds and elemental halogen occluded impurities to ionic halogen materials;
- and
- c. separating the ionic halogen materials from the brominated polymers.
Dependencies are inferred from the claim text.