Method and apparatus for manufacturing tubular film from thermoplastic resin

Claim 1

A METHOD OF MANUFACTURING TUBULAR FILM FROM THERMOPLASTIC RESIN COMPRISING: A. EXTRUDING THERMOPLASTIC RESIN THROUGH AN ANNULAR DIE PRODUCING INFLATED TUBULAR FILM; B. CONDUCTING SAID TUBULAR FILM GENERALLY DOWNWARDLY FROM SAID DIE AND SIMULTANEOUSLY COOLING IT EXTERNALLY AND INTERNALLY; C. SIZING THE TUBULAR FILM BY APPLYING VACUUM AROUND THE EXTERNAL SURFACE THEREOF IN A ZONE SUBSTANTIALLY IMMEDIATELY BEFORE THE FILM BEGINS TO CRYSTALLIZE AS A RESULT OF SAID COOLING; D. SAID EXTERNAL COOLING OF THE FILM COMPRISING: A. CONTACTING THE EXTERNAL SURFACE OF SAID FILM ABOVE SAID ZONE WITH A FIRST STREAM OF COOLING LIQUID THAT FLOWS COUNTERCURRENTLY TO THE DIRECTION OF TRAVEL OF SAID FILM, B. CONTACTING THE EXTERNAL SURFACE OF SAID FILM BELOW SAID ZONE WITH A SECOND STREAM OF COOLING LIQUID THAT FLOWS COCURRENTLY WITH THE DIRECTION OF A TRAVEL OF SAID FILM, C. WITHDRAWING SAID FIRST STREAM OF LIQUID FROM CONTACT WITH THE FILM AT A CONTROLLED UPPER LEVEL LOCATED ABOVE SAID ZONE, D. WITHDRAWING SAID SECOND STREAM OF LIQUID FROM CONTACT WITH SAID FILM DOWNSTREAM OF SAID ZONE, E. SAID INTERNAL COOLING OF THE FILM BEING CONDUCTED BY CONTACTING THE INTERNAL SURFACE OF SAID FILM WITH A MANDREL THEREIN THE UPPER PERIPHERY OF WHICH IS SUBSTANTIALLY IN THE PLANE OF SAID CONTROLLED UPPER LEVEL OF WITHDRAWAL OF FIRST STREAM OF LIQUID; AND F. TAKING UP THE RESULTING TUBULAR FILM.

Claim 2

A METHOD OF MANUFACTURING TUBULAR FILM FROM THERMOPLASTIC RESIN COMPRISING: A. EXTRUDING THERMOPLASTIC RESIN THROUGH AN ANNULAR DIE PRODUCING INFLATED TUBULAR FILM; B. CONDUCTING SAID TUBULAR FILM GENERALLY DOWNWARDLY FROM SAID DIE AND SIMULTANEOUSLY COOLING IT EXTERNALLY AND INTERNALLY; C. SIZING THE TUBULAR FILM BY APPLYING VACUUM AROUND THE EXTERNAL SURFACE THEREOF IN A ZONE SUBSTANTIALLY IMMEDIATELY BEFORE THE FILM BEGINS TO CRYSTALLIZE AS A RESULT OF SAID COOLING; D. SAID EXTERNAL COOLING OF THE FILM COMPRISING: A. CONTACTING THE EXTERNAL SURFACE OF SAID FILM ABOVE SAID ZONE WITH A FIRST STREAM OF COOLING LIQUID THAT FLOWS COUNTERCURRENTLY TO THE DIRECTION OF TRAVEL OF SAID FILM, B. CONTACTING THE EXTERNAL SURFACE OF SAID FILM BELOW SAID ZONE WITH A SECOND STREAM OF COOLING LIQUID THAT FLOWS COCURRENTLY WITH THE DIRECTION OF A TRAVEL OF SAID FILM, C. WITHDRAWING SAID FIRST STREAM OF LIQUID FROM CONTACT WITH THE FILM AT A CONTROLLED UPPER LEVEL LOCATED ABOVE SAID ZONE, D. WITHDRAWING SAID SECOND STREAM OF LIQUID FROM CONTACT WITH SAID FILM DOWNSTREAM OF SAID ZONE, E. SAID INTERNAL COOLING OF THE FILM BEING CONDUCTED BY CONTACTING THE INTERNAL SURFACE OF SAID FILM WITH A MANDREL THEREIN THE UPPER PERIPHERY OF WHICH IS SUBSTANTIALLY IN THE PLANE OF SAID CONTROLLED UPPER LEVEL OF WITHDRAWAL OF FIRST STREAM OF LIQUID; AND F. TAKING UP THE RESULTING TUBULAR FILM.

Claim 8

A method of manufacturing a tubular film from thermoplastic resin comprising: A. conducting a tubularly inflated film extruded through an annular die downwardly into a cylindrical water cooler; B. supplying cooling wAter from the outside of the film in said water cooler to provide both upward and downward streams of the cooling water, the external surface of the film coming into contact first with said upward stream and then with said downward stream; C. sizing the tubular film by applying vacuum thereon substantially immediately before the film begins to crystallize after contact with said cooling water; D. cooling internally the tubular film by a mandrel disposed therein at a position substantially equal to said water cooler; E. overflowing the upward stream of cooling water from said water cooler in such a manner as to fix the point at which the tubular film is initially cooled with cooling water; F. drawing the downward stream of cooling water from the lower portion of said water cooler; and G. taking up the finished tubular film.

Claim 9

A method of manufacturing a tubular film from thermoplastic resin comprising: A. conducting a tubularly inflated film extruded through an annular die downwardly into a cylindrical water cooler; B. supplying cooling wAter from the outside of the film in said water cooler to provide both upward and downward streams of the cooling water, the external surface of the film coming into contact first with said upward stream and then with said downward stream; C. sizing the tubular film by applying vacuum thereon substantially immediately before the film begins to crystallize after contact with said cooling water; D. cooling internally the tubular film by a mandrel disposed therein at a position substantially equal to said water cooler; E. overflowing the upward stream of cooling water from said water cooler in such a manner as to fix the point at which the tubular film is initially cooled with cooling water; F. drawing the downward stream of cooling water from the lower portion of said water cooler; and G. taking up the finished tubular film.