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Abstract

A process for the simultaneous drying and crystallization of crystallizable thermoplastic synthetic material (plastic), e.g. polyethylene terephthalate, in which plastic from the melt is extruded in cord form, solidified at the surface by quenching in water and crystallized by gas treatment and dried, using a device for cooling and drying the cord emerging from dies having a casting gutter with its acceptance end arranged beneath the dies and a device producing a flow of coolant on the casting gutter within a quenching section, a subsequent dewatering section in which the casting gutter has apertures for the free flow of the coolant, a subsequent drying section in which the casting gutter has closely spaced nozzles for the passage of gas and a granulator downstream of the drying section. The lengths of the quenching, dewatering and drying sections must be such, taking account of the rate of creep of the cord along the casting gutter, that the passage time in the quenching section is a maximum of some 1.5 seconds to attain a cord surface temperature of at least 100.degree. C., in the dewatering section at most some 0.1 second and in the drying section at most about 20 seconds for crystallization, with the surface temperature at the end of the quenching section largely maintained.

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First Claim