Pre-foamed particles of polypropylene resin and process for prod

Details Pre-foamed particles of polypropylene resin and process for prod Pre-foamed particles of polypropylene resin and process for prod

1981-11-19

1983-04-12

Foelak, Morton

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

Synthetic resins

Cellular products or processes of preparing a cellular...

521 56, 521 60, 521134, 521144, C08J 918

Patent

active

043798594

ABSTRACT:
Substantially non-crosslinked pre-foamed particles of a polypropylene resin, characterized by the fact that they are composed of an ethylene/propylene random copolymer or a mixture of an ethylene/propylene random copolymer with low density polyethylene and/or an ethylene/vinyl acetate copolymer as a base resin; and a process for producing pre-foamed particles of a polypropylene resin, which comprises dispersing substantially non-crosslinked particles of the polypropylene resin composed of an ethylene/propylene random copolymer or a mixture of an ethylene/propylene random copolymer with low-density polyethylene and/or an ethylene/vinyl acetate copolymer and a volatile blowing agent in water in the presence of a dispersing agent within a closed vessel; heating the dispersion to a temperature above a temperature at which the resin particles soften, thereby to impregnated the blowing agent in the resin particles; and while maintaining the pressure of the inside of the vessel higher than the vapor pressure of the blowing agent, opening one end of the vessel to release the resin particles and water simultaneously into an atmosphere kept at a lower pressure than the inside of the vessel.

REFERENCES:
patent: 3616365 (1971-10-01), Stastny et al.
patent: 3709806 (1973-01-01), Minomi et al.
patent: 3743611 (1973-07-01), Muroi et al.
patent: 4168353 (1979-09-01), Kitamori
patent: 4303756 (1981-12-01), Kajimura et al.
patent: 4303757 (1981-12-01), Kajimura et al.

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