POLYMERIZATION INHIBITOR FOR AROMATIC VINYL COMPOUNDS AND METHOD FOR INHIBITING THE POLYMERIZATION OF THE COMPOUNDS

According to the present invention, there are provided a polymerization inhibitor which is easy to handle and which has a little toxicity and a high polymerization-inhibitory effect toward an aromatic vinyl compound and a process for inhibiting the polymerization of the aromatic vinyl compound. The present invention relates to a polymerization inhibitor for the aromatic vinyl compound which comprises contain two ingredients of a specific quinone methide compound and a specific organic sulfonic acid compound, and to a process for inhibiting polymerization of the aromatic vinyl compound which comprises adding a specific quinone methide compound and a specific organic sulfonic acid compound simultaneously or further a specific quinone methide compound, a specific organic sulfonic acid compound and a specific N-oxyl compound simultaneously in the stage of producing, purifying, storing or transporting the aromatic vinyl compound.