Process for the polymerization of vinyl chloride

Abstract

In a process for the aqueous suspension polymerization of vinyl chloride, alone or in mixture with other monomers, in the presence of at least one of dialkylperoxydicarbonate, peroxyester and diacyl peroxide, the polymerization composition according to the invention comprises at least one dialkylhydroxylamine as a shortstopping agent along with a totally or partially hindered phenolic antioxidant.

1 . A process for the aqueous suspension polymerization of vinyl chloride, alone or as a mixture with less than 50% of another vinyl monomer, in the presence of a polymerization initiator comprising at least one compound chosen from dialkyl peroxydicarbonates, peroxy-tert-alkanoates and diacyl peroxides, characterized in that use is made of a polymerization regulating agent comprising at least one mono- or di alkyl substituted N hydroxylamine having the formula:
   HO—N—R 1 R 2  
   wherein R 1  and R 2  may be the same or different, and are selected from H and C 1 -C 12  hydrocarbons, where each hydrocarbon chain may be branched, unsaturated, or have hydrogen substituted with functional groups selected from —OH, —SO, benzyl, amino, mercapto, keto, carboxyl, or where R 1  and R 2  may form together a cyclic structure, with the proviso that at least one of R 1  and R 2  is different from H in the amount of 0.0005 to 0.1 parts by weight per 100 parts by weight of monomers, along with a totally or partially hindered phenolic antioxidant.   
     
     
         2 . The process according to  claim 1 , characterized in that the polymerization regulating agent comprises a dialkylhydroxylamine in which each alkyl radical comprises from 1 to 4 carbon atoms. 
     
     
         3 . The process according to  claim 2 , characterized in that the polymerization regulating agent comprises diethylhydroxylamine 
     
     
         4 . The process according to  claim 1 , characterized in that the polymerization initiator comprises a dialkyl peroxydicarbonate in which each alkyl radical comprises from 1 to 16 carbon atoms. 
     
     
         5 . Process according to  claim 1 , characterized in that the antioxidant is chosen from butylated hydroxyanisole, butylated hydroxytoluene, 2,4-dimethyl-6-sec-hexadecylphenol, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,6-di-tert-butyl-4-sec-butylphenol, 3,5-di-t-butyl-4-hydroxy-hydrocinnamic acid C 7 -C 9  alkylester and mixtures of 2,4-dimethyl-6-sec-hexadecylphenol and octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. 
     
     
         6 . Polymerization regulating agent for use in a process for the aqueous suspension polymerization of vinyl chloride, alone or as a mixture with less than 50% of another vinyl monomer, using a polymerization initiator comprising at least one compound chosen from dialkyl peroxydicarbonates, peroxy-tert-alkanoates and diacyl peroxides, characterized in that said polymerization regulating agent comprises at least one mono- or di alkyl substituted N hydroxylamine having the formula:
   HO—N—R 1 R 2  
   wherein R 1  and R 2  may be the same or different, and are selected from H and Ci-C12 hydrocarbons, where each hydrocarbon chain may be branched, unsaturated, or have hydrogen substituted with functional groups selected from —OH, —SO, benzyl, amino, mercapto, keto, carboxyl, or where R 1  and R 2  may form together a cyclic structure, with the proviso that at least one of R 1  and R 2  is different from H. in the amount of 0.0005 to 0.1 parts by weight per 100 parts by weight of monomers, along with a totally or partially hindered phenolic antioxidant.   
     
     
         7 . Polymerization regulating agent according to  claim 6 , characterized in that the polymerization regulating agent comprises a dialkylhydroxylamine in which each alkyl radical comprises from 1 to 4 carbon atoms. 
     
     
         8 . Polymerization regulating agent according to  claim 7 , characterized in that the polymerization regulating agent comprises diethylhydroxylamine 
     
     
         9 . Polymerization regulating agent according to  claim 6 , characterized in that the antioxidant is chosen from butylated hydroxyanisole, butylated hydroxytoluene, 2,4-dimethyl-6-sec-hexadecylphenol, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,6-di-tert-butyl-4-sec-butylphenol, 3,5-di-t-butyl-4-hydroxy-hydrocinnamic acid C 7 -C 9  alkylester and mixtures of 2,4-dimethyl-6-sec-hexadecylphenol and octadecyl-3-(3,5-di-tert-butyl-4hydroxyphenyl)propionate.