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US 5,888,356 AGranted
Inhibition of polymerization of vinylaromatic or vinylaliphatic
AssigneeHuels Aktiengesellschaft
InventorsThomas Keil, Manfred Kaufhold, Bernd Helpap
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Abstract
The polymerization of a vinylaromatic or vinylaliphatic compound at elevated temperature in the absence of air is inhibited by processing the vinylaromatic or vinylaliphatic compound in the presence of 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl or 4-acetylamino-2,2,6,6-tetramethylpiperidine-N-oxylalone or in admixture with p-nitrosophenol or 2-methyl-4-nitrosophenol.
Claims9
A method of inhibiting the polymerization of a vinylaromatia or vinylaliphatic compound, comprising:
- vacuum distilling said vinylaromatic or vinylaliphatic compound at an elevated temperature of 90.degree.-140.degree. C. under conditions which exclude air in the presence of an inhibitor which is a) 4-acetylamino-2,2,6,6-tetramthylpiparidine-N-oxyl, b) 4-acetylamino-2,2,6,6-tetramethylpiparidine-N-oxyl mixed with p nitrosophenol or c) 4-acetylamino-2,2,6,6-tetramethylp piperidine-N-oxyl mixed with 2-methyl-4-nitrosopheno.
A method of inhibiting the polymerization of a vinylaromatic or vinylaliphatic compound, comprising:
- vacuum distilling said vinylaromatic or vinylaliphatic compound at an elevated temperature of 90.degree.-14020 C. under conditions which exclude air in the presence of an inhibitor which is 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl in admixture with p-nitrosophenol or 2-methyl-4-nitrosophonol, wherein the ratio of the piperidine-N-oxyl compound to said nitrosophenol compound ranges from 90:10-10:90.
Dependencies are inferred from the claim text.