Line blowing and printing technology

PE material when it comes to plastic bag factories is usually in the form of plastic granules, before PE material is produced, it can be further processed with some additives to increase some features such as:
- EPI and D2W (1-2%) to make biodegradable bags.
- Anti-blocking agent: used to prevent plastic film layers from sticking together, in addition,
it makes it easier for thin LDPE bags to open (smooth, slide 2 layers on top of each other).
- UVI (Ultraviolet): is an anti-ultraviolet agent, this is a type of radiation that can reduce mechanical strength and make
color fade nylon bag.

Plastic bags are made from PolyEthylene (PE) material. And the production process consists of three main steps: extrusion-blowing, printing of cheap plastic bags and finishing design:

Step 1: Extrusion - blowing film
This is the most important step in the production process of plastic bags.
Plastic granules are fed into a blow extruder, where they are then melted under controlled conditions to make them molten and pliable (about 380oF). They are then pressed - extruded through a tube mold.
While at high temperatures one outlet of the tube is fixed and air blows in to form bubbles and is elevated, the tube will stretch to the desired size and thickness.
When about 20 - 35 feet high, the film cools and is formed into a 2-layer flat form when passing through the shaft gap including 2 rollers. It is then rolled into film rolls.

Step 2: Stitching printing
The film rolls are passed through the plastic bag printer unit. Depending on the maket design and the number of printed colors and the number of printed bags... the printing of plastic bags will be handled by screen printing, gravure or flexographic printing.

However, if printing large bags, gravure printing is the most suitable.