Plastic bags, also called “poly bags,” are one of those modern conveniences we can’t take for granted. The production process of plastic bags is a question that many people are interested in. In this article, we will introduce to our readers “How are plastic bags produced?”
Anti-block—Prevents the plastic layers from sticking together (blocking).
Slip—Helps the plastic bag open easier and allows items to slide in smoothly.
Ultraviolet Inhibitor (UVI)—Protects the plastic from ultraviolet radiation, which can weaken the plastic’s strength and fade its color.
The polyethylene arrives at the plastic bag manufacturing facility in pellet form, referred to as resin.
Terms Used by Plastic Bag Suppliers
Blocking: A condition that occurs when very flat or smooth surfaces placed against each other will adhere together. Also called “cohesion.”
Die: A mold that produces a desired shape. In blown film extrusion, the die shape is circular.
Extruder: A pump for very thick fluids. The extruder contains a rotating screw that mixes and melts the material.
Frostline (or freeze line): The point where molten polyethylene solidifies into a film.
Gusset: Indentations in the sides of plastic bags that allow the bag to lay flat when stored but expand when opened.
Layflat Form: Tubular poly film that’s been flattened for rolling and further processing.
Nip Rolls: Two motorized rolling pins at the top of the cooling tower that pull the poly film upward.
Polyethylene: A type of thermoplastic resin made by altering the molecules of ethylene gas.
The machine used to create the plastic bags is an extruder and die assembly.