Process and apparatus for producing sheet film from tubular ther

Details Process and apparatus for producing sheet film from tubular ther Process and apparatus for producing sheet film from tubular ther

1972-06-23

1977-01-18

Thurlow, Jeffery R.

Plastic and nonmetallic article shaping or treating: processes

Vacuum treatment of work

264146, 264178R, 264235, 264237, 264348, 425 71, 425326R, B29D 720, B29C 2500

Patent

active

040039730

ABSTRACT:
A sheet film is produced from a tubular thermoplastic resin film by cooling a molten tubular film of crystalline thermoplastic resin, for example, polypropylene, extruded downward from an annular die in direct contact simultaneously with cooling liquids on the outside and inside of the film, the cooling liquid on the outside being in an outside cooling liquid tank and in contact with the outside of the film and the cooling liquid on the inside flowing down along the surface of a mandrel provided through the outside cooling liquid tank and in contact with the inside of the film, a liquid level of the cooling liquid on the inside being kept higher by 5-15 mm than that of the cooling liquid on the outside; cutting open length wise one or two side ends of the film just before being flattened and folded by nip rolls thereby to discharge the cooling liquid from the inside; and removing the liquid attached to the surfaces of the resulting sheet films withdrawn by the nip rolls promptly. The sheet films having a good transparency, good flatness and less uneveness in thickness can be thereby produced at a high speed.

REFERENCES:
patent: 2433937 (1948-01-01), Tornberg
patent: 2955318 (1960-10-01), Cook et al.
patent: 3008185 (1961-11-01), Goldman
patent: 3090991 (1963-05-01), Hathaway
patent: 3108324 (1963-10-01), Zavasnik
patent: 3193547 (1965-07-01), Schott, Jr.
patent: 3450806 (1969-06-01), Matsuo et al.
patent: 3579618 (1971-05-01), Stewart et al.
patent: 3655846 (1972-04-01), Kanoh et al.

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