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AssigneeNippon Shokubai Co., Ltd.
InventorsKazuhiko Sakamoto, Tomohiro Nakae, Kazuo Okochi, Masahiro Uemura, Sei Nakahara
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This method of preventing polymerization of methacrylic acid inn the process of its production is characterized by comprising using, in a refining column, a combination of N-nitrosophenylhydroxylamine or salt thereof with an N-oxyl compound, an N-hydroxy-,2,2,6,6-tetramethylpiperidine compound and a 2,2,6,6-tetramethylpiperidine compound. In this method, N-nitrosophenylhydroxylamine or a salt thereof rises inside a refining column under splitting part thereof to effectively inhibit polymerization of (meth)acrylic acid or the like. The above polymerization in both vapor and liquid phases can be inhibited more effectively by the combined use of the compounds mentioned above.
A method for preventing the polymerization of (meth)acrylic acid and esters thereof, comprising the step of using (i) an N-nitrosophenylhydroxylamine or a salt thereof, (ii) an N-oxyl compound, (iii) an N-hydroxy-2,2,6,6-tetramethylpiperidine compound, and (iv) a 2,2,6,6-tetramethylpiperidine compound in combination in a purifying column.
Dependencies are inferred from the claim text.