MX167900B - PROCEDURE FOR PRODUCING STABILIZED POLYETHYRENE COMPOSITIONS - Google Patents

Abstract

The present invention relates to a process for the production of selected polymeric compositions of polystyrene and poly (p-methylstyrene) having improved stability against degradation, the process comprises subjecting styrene or p-methylstyrene monomer or thermal polymerization with or without the addition of free radical polymerization initiators to achieve a monomer to polymer conversion of at least about 65 percent by weight and to recover the thus formed polymer, characterized in that a polymer stabilizer solution or suspension is added to the monomer or polymerizing mixture At a point in the process where further conversion of monomer to polymer of not less than about 3 percent has yet to occur, the polymer stabilizer is a mixture of a hindered phenol compound and a polyphosphite compound in an amount by weight of hindered phenol compound to p compound oliphosphite from about 1: 2 to about 1: 4, the amount of polymer stabilizer is such that it provides from about 0.1 to about 6 weight percent based on polystyrene or poly (p-methylstyrene), the hindered phenol compound is selected from the group consisting of 2,6-di-ter, butyl-4-methyl phenol, and phenol compounds having at least 2 and not more than 4 groups of phenol, each phenol group is linked directly or through a group alkylene, alkoxy or ryl of a carbon atom from an aromatic ring to a carbon atom of the aromatic ring of at least one other phenol group and each phenol group has on the aromatic ring at least one alkyl substituent comprising at least an ortho tertiary butyl group relative to the hydroxy group, the polyphosphite compound is chosen from the group consisting of compounds having 2 to 8 phosphite groups, each compound having each phosphorus atom linked directly to the three atoms of oxygen separated whose oxygen atoms are also directly linked to a carbon atom of an alkyl, aryl, alkoxy or aryloxy group.