Anti-static Treatment of The Packaging Film of The Transparent Film Three-dimensional Packaging Machine

The anti-static treatment of packaging film in the transparent film three-dimensional packaging machine is of vital importance. The following are the specific treatment methods and related analyses:

Physical elimination method

The physical elimination method is to eliminate static electricity by taking advantage of the inherent characteristics of static electricity itself without changing the material's performance.

Grounding elimination method: Install the anti-static brush on the process, place the brush body at the winding or unwinding point of the plastic roll, and ensure that the grounding terminal of the anti-static brush is reliably grounded. It must not be connected to the equipment or guide rollers. Because the equipment may have poor grounding, some guide rollers have undergone anodic treatment, generating aluminum oxide on the surface, and aluminum oxide is non-conductive. For instance, installing an electrostatic brush assembly on the packaging machine body, which includes a bracket, a first motor, electrostatic brushes, a rotating shaft and a lead screw jack, can effectively remove static electricity from the transparent film.

Installation of the static eliminator: Install an ion rod at the position before the film packaging of the product. If the unfolded film has not left the reel or is still wound around the drum, ion rods need to be installed after the film is unfolded to neutralize static electricity. For instance, in a sleeve labeling machine, an ion rod should be installed at a position that avoids the machine components but can neutralize the static electricity when opening the membrane tube. The ideal distance between the ion rod and the membrane tube is 50mm, and an ion rod should be installed on each side of the membrane tube.

Electrostatic ball application: By starting the motor to drive the second lead screw to rotate, it then moves the first fixed plate. The first fixed plate drives the fixed ring and the electrostatic ball to move, causing the electrostatic ball to move back and forth above the film, thereby removing static electricity and achieving the purpose of eliminating static electricity without dead corners.

Chemical elimination method

The chemical elimination of static electricity method, also known as the antistatic agent treatment technology, mainly involves the addition of antistatic agents or coating techniques to modify the performance of resins or substrates.

Additive processing technology: Additive antistatic agents are mixed with thermoplastic resins at a certain concentration, and various additives are added. After melting, blending and granulation, antistatic masterbatches are produced. During the production process of BOPP films, the addition of antistatic agents and antistatic masterbatches can solve the static electricity problem from the source. The selection of antistatic agents should pay attention to their compatibility with the base resin. If the compatibility is too poor, the performance of the antistatic particles produced will be poor. However, if the compatibility is too good, the migration speed of the antistatic agent to the surface will be too slow, making it difficult to form an antistatic water film. The preparation of anti-static plastic films using anti-static particles often adopts a three-layer co-extrusion blow molding process. The proportion of anti-static masterbatch added should be determined based on the concentration of its active ingredient, and appropriate adjustments should be made according to the test results to keep the surface resistivity around 1011Ω. An increase in the addition amount not only raises the product cost but also has an adverse effect on the subsequent processing procedures.

Coating type treatment technology: Ionic surfactants are made into anti-static coatings and applied to the surface of plastic films to prevent the accumulation of electric charges. The selection of coating-type antistatic agents should be determined based on the work function of the substrate to be coated. If the work function of plastic materials is large, they are prone to negative charge. If its work function is small, it is positively charged. For instance, PP and PE are highly prone to negative charges, and it is advisable to use cationic surfactants for coating. PET and PA are highly prone to positive charge, and it is advisable to use anionic surfactants for coating. Meanwhile, the surface wetting tension of the plastic film should be greater than 38dyn/cm. The anti-static coating should have good film-forming properties, be resistant to friction and chemical erosion, and have a long-lasting effect.

Environmental regulation method

An environment with high humidity is conducive to the elimination of static electricity on the film surface. During dry seasons (such as winter), enterprises can place the film in the packaging workshop in advance to regulate the humidity of the packaging workshop. They can also wet the workshop floor with water or cover the end face of the film roll with a wet towel to increase the humidity of the environment and eliminate static electricity on the surface of the film.