Pre-expanding process and apparatus for the same

Details Pre-expanding process and apparatus for the same Pre-expanding process and apparatus for the same

1984-09-06

1985-06-18

Foelak, Morton

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Cellular products or processes of preparing a cellular...

264 53, 264DIG9, 521 56, 521 68, C08J 922

Patent

active

045241546

ABSTRACT:
A process for preparing pre-expanded particles of a thermoplastic resin which comprises; heating under an elevated pressure an aqueous dispersion comprising thermoplastic resin particles containing a volatile foaming agent and an aqueous medium in a pressure vessel; releasing the dispersion from the pressure vessel into a space within a sealed low-pressure vessel wherein the pressure is lower than that in the pressure vessel and the space is sealed with an aqueous medium which exists in the lower portion of the vessel and communicates with the outside of the vessel, whereby expanding the thermoplastic resin particles to give pre-expanded particles; and sinking the resulting pre-expanded particles under the aqueous medium by means of a rotary impeller provided in the pressure vessel so that the pre-expanded particles are taken out of the low-pressure vessel through the aqueous medium towards the outside of the vessel, while recovering the foaming agent volatilized from the thermoplastic resin particles by discharging the foaming agent out of the space in the low-pressure vessel with controlling the pressure in the low-pressure vessel to substantially a given pressure. According to the process, the release of the volatile foaming agent in the air is prevented, the productivity is increased and extraneous matters on the pre-expanded particles are removed.

REFERENCES:
patent: 3577360 (1971-05-01), Immel
patent: 4436840 (1984-03-01), Akiyama et al.
patent: 4448901 (1984-05-01), Senda et al.
patent: 4464484 (1984-08-01), Yoshimura et al.

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