초록 ▼

In the manufacture of plastic bags having interlocking profiled extrusions for the closure, the extruded plastic profile is applied to the moving web of film immediately after extrusion of the profile. The temperature of the moving web is maintained such that the profile adheres to the moving web up

In the manufacture of plastic bags having interlocking profiled extrusions for the closure, the extruded plastic profile is applied to the moving web of film immediately after extrusion of the profile. The temperature of the moving web is maintained such that the profile adheres to the moving web upon contact and thereafter cools to set the thermoplastic in the desired profile. The moving web of film is maintained under tension so that contraction of the film upon release compensates for the contraction of the locking profile as it cools to prevent puckering of the web. The locking profile is applied to the web in an in-line process which includes folding and heat sealing the moving web of film to form plastic bags.

대표청구항 ▼

Apparatus for attaching locking profile extrusions to a plastic film comprising: means for moving a web of said film; an extruding assembly positioned adjacent to said moving web comprising first and second means for extruding first and second locking plastic profiles and means for supplying molten

Apparatus for attaching locking profile extrusions to a plastic film comprising: means for moving a web of said film; an extruding assembly positioned adjacent to said moving web comprising first and second means for extruding first and second locking plastic profiles and means for supplying molten thermoplastic to said extruding assembly; means for maintaining the temperature of said moving web sufficiently high so that said profiles adhere to said moving web upon contacting and thereafter cool to set said thermoplastic in said profiles; and means for maintaining said moving web under tension about a cylindrical roller including a first nip roller for biasing said moving web against said cylindrical roller prior to said moving web coming into contact with said profiles and a second nip roller for biasing said moving web against said cylindrical roller after said profiles come into contact with said moving web, so that contraction of said film upon release compensates for the contraction of said profiles as said profiles cool to prevent puckering of said moving web. A method of attaching locking profile extrusions to a plastic film comprising: moving a web of said film past an extruding assembly; extruding from said extruding assembly first and second locking plastic profiles of molten thermoplastic onto said moving web; maintaining the temperature of said moving web sufficiently high so that said profiles adhere to said moving web upon contacting and thereafter cool to set said thermoplastic in said profiles; and maintaining said moving web under tension about a cylindrical roller with a first nip roller for biasing said moving web against said cylindrical roller prior to said moving web coming into contact with said profiles and with a second nip roller for biasing said moving web against said cylindrical roller after said profiles come into contact with said moving web, so that contraction of said film upon release compensates for the contraction of said profiles as said profiles cool to prevent puckering of said moving web.