Process and apparatus for reducing color contamination in the process recycle of zippered thermoplastic bags.

摘要

Disclosed are a process and apparatus for eliminating the problem of color contamination during product recycle in the manufacture of reclosable thermoplastic bags having zippers of a color different than that of the remainder of the bag. Process and apparatus for effecting same include extrusion of the colored thermoplastic material from a separate, smaller secondary extruder to avoid process shutdown during recycle, encapsulation of the colored thermoplastic material within the colorless flow melt to enhance transport of the colored flow melt, and placement of a dump valve between the secondary extruder and the feedblock to controllably interrupt the flow of the colored flow melt as desired. Further disclosed are an apparatus and process for effecting encapsulation of the colored flow melt.