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Luperox® for Polymerization of Vinyl Chloride

 

A Range of Solutions

The wide range of Luperox® organic peroxides is well adapted to suspension process for polymerizations of vinyl chloride.  The reaction is generally performed between 40 and 80°C over 3 to 10 hours. The molecular weight and density of the polymer can be regulated by temperature in the reactor. Temperature is constant during polymerization for a given grade, for example, K-67 is typically manufactured at 57°C.

 

 

Process

Suspension polymerization represents 80% worldwide production. The main characteristics of this process are:

 

  • Batch technology
  • Reaction in water, liquid vinyl chloride in droplets of lower than 50 µm
  • Autoclave reactor: 8-12 bars, 50 - 70°C
  • Polymerization conducted up to 75% conversion
  • Reaction finished or stopped at about 90% conversion

Peroxide Selection

The best productivity in vinyl chloride polymerization is achieved when the thermal energy generated by peroxide decomposition is as constant as possible. For this reason, a selection of several peroxides is recommended:

 

  • A high activity, short half-life peroxide to quickly start the reaction
  • A medium half-life peroxide to continue the reaction
  • A long half-life peroxide to achieve good monomer conversion

 

Half-Life (°C) Peroxide Recommended K Value Reaction Temperature (°C) Application
54-58
  • Luperox® 610M75
  • Luperox® 188M75
≥ 70 < 54 Flexibles
64-66
  • Luperox® 223-S
  • Luperox® 223M75-S
  • Luperox® 10
≥ 67 57 Pipe/Profile
72-81
  • Luperox® 554M75
  • Luperox® 11M75
  • Luperox® 219M75
  • Luperox® LP
≥ 62 > 60 Rigid Film/Sheet

Peroxide Emulsions

Emulsions of peroxide in water offer unique advantages:

 

  • Water in the formulation acts as a heat-sink, reducing risk of ignition
  • Fish-eyes in the resins can be reduced
  • Faster dispersion in the reactor
  • Improvements in waste water treatment

 

Arkema is offering a range of emulsions to the PVC industry.