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Process description

The SUNKAIER EPS technology is based on a batch suspension polymerization of styrene, with an inorganic suspending agent. The internal chemicals are dissolved in styrene. This preheated solution is afterwards transferred into a reactor, pre-filled with demiwater and suspending agent, under agitation.
Polymerisation starts and continues till, to a certain polymer content, the blowing agent is added. The reaction goes ahead untill the residual styrene reaches the target value, according to a proper temperature cycle and recipe. Final bead size is chemically controlled during the polymerisation up to the desired diameter.
The small amount of blowing agent escaping from the polymerisation section is sent to a flare. After polymerisation, EPS bead slurry is cooled to an intermediate temperature and then transferred to pressurised cooling tanks, where it reaches the final discharge temperature. The slurry is then transferred
into a bigger slurry tank, capable to contain several batches, in order to get a good homogeneity and to continuously feed the centrifugation section. Wet beads are then still continuously fed to a drier and to the screening section to be classified in the desired grades. All the waste water can be treated by a common byological plant.
Single fractions are temporary stored in silos and batch wise lubricated with a proper coating recipe. All the residual amounts of the coated fractions (e.g. excess weights of the lubricating section) can be recovered in the slurry tank section.

Process design advanced features

Polymerization section

  • Proprietary reactor design able to give narrow bead size distributions; high reactor filling and no need for chemical washing.
  • Proprietary suspension system based on an inorganic agent, able to:

                      – get an optimal control on bead size distribution and bead internal cellular structure;
                      – stabilize the small styrene droplets, avoiding the risk of agglomeration during the polymerisation cycle.

  • Single step technology the impregnation of the beads with pre-foaming agent is made during the polymerisation step, thus avoidinga further and expensive steeping phase.
  • Wide bead size range from 0.2 to 3 mm; a typical narrow size distribution (s/x) of 0.18 can be obtained for any bead size.
  • Easy availability in the world market of the chemical used in the process.

Coating section

  • Highly developed coating deposition technology able to tailor EPS grades to the desired customer needs.