Relevant introductions about the composition of plastic bags: Commonly used food plastic bags are mostly made of polyethylene film, which is non-toxic, so it can be used to hold food. There is also a kind of film made of polyvinyl chloride, polyvinyl chloride itself is non-toxic, but the additives added according to the purposes of the film are often harmful substances to the human body and have certain toxicity. Therefore, this kind of film and the plastic bag made of this film are not suitable for holding food. If you want to identify polyvinyl chloride plastic bags and polyethylene plastic bags, you can use the following simple method for identification.

Polyethylene film (non-toxic)

The film is milky white, translucent (especially when several layers are stacked and observed), and feels smoother, as if the surface is coated with a wax layer. When shaken vigorously, the sound is brittle. It is flammable in case of fire, and the flame is yellow. When burning, mucus drips , and has the smell of burning candles.

PVC film (generally toxic)

If no pigment is added, it will be transparent, and the surface will feel a little sticky. If you shake it vigorously, the voice will be low.

The processing and production of plastic bags is relatively simple on the surface. You only need to configure a blow molding machine, a bag making machine or hand-made bags. If you need to print, you can use a printing machine. The three raw materials you mentioned are commonly used materials. The key is the sales volume. The price is generally calculated according to KG. The volume can be calculated according to the length, width and thickness of the plastic bag. The specific gravity of polyethylene is generally around 1. The exact point can be calculated by multiplying the weight by 0.93, and then multiplying by the raw material. Just a single price.