Analysis of the Generation and Elimination of Static Electricity in Packaging Printing

First, the generation of static electricity

In addition to the natural phenomenon of static electricity generated by lightning, it is the physical friction generated by static electricity. In theory, when the surface of one material is released or the surface of another material is contacted or separated on a daily basis, the electrons will be transferred from one material to another. The electron-accepting surface will be negatively charged and lose electrons. The surface of the material is positively charged.

In fact, due to the influence of electrostatically generated materials, environmental conditions, mechanical action, and process requirements, the generation of static electricity is irregular and is constantly reflected on the surface of the material. In other words, the surface of the same material that generates static electricity may have a part of positive charge, a part of it may have negative charge, or it may be that part of the electrostatic potential of the same material surface is high, and part of the potential is low.

In general, a good insulating plastic sheet is prone to static electricity during production and processing, followed by paper, and conductive or semi-conductive materials rarely generate static electricity.

Second, the elimination of static electricity

1. The harm of static electricity:

When the voltage of the static electricity is too high, the ionized air easily reacts chemically with the solvent in the production floor to catch fire or shock the production personnel. In print/composite manufacturing processes, quality problems such as dusting occur due to static electricity in the material.

Static elimination method

A, ground with copper wire

Only a small part of the charge can be taken away. It can only be used in low-speed production lines and it is in direct contact with the material. It can easily scratch the surface of the material or cause sparks and fire.

B, fiber carbon brush / static cloth

It can be used for static elimination with low electrostatic charge in low and medium production lines. The same can only take away some of the charge, and the actual life is short, because it is easy to absorb dust and make it ineffective.

C, humidification

Increasing the air humidity in the production plant can reduce static electricity, but for printing/compounding processes, increasing the humidity will cause the paper fibers to change, affecting the printing/composite quality.

D. General discharge or static eliminator

Most static elimination generators use direct current, except for static charges, which can only be positive, so they can only neutralize negative charges. When the surface of the material has a positive charge or both positive and negative charges, static electricity cannot be completely taken away, but the static voltage is higher and higher. This is also why many customers report that their use of static eliminators is sometimes bad at times.

However, some electrostatic generators using alternating currents are not suitable because of static electricity and negative charge release due to the design of static electricity. The current is too high to make the static elimination effect unsatisfactory, and it is not suitable for high-speed production lines. Because the current of the electrostatic stick is too high, there is a danger of the operator operating in the vicinity of it and it is not suitable for labor safety. Germany [LTEX static elimination device adopts alternating current, high voltage and low current principle. Electrostatic elimination generators up to 5000 volts/8000 volts and even higher voltages output only 0.1 mA of current in the static bar. Even if the static electricity stick is held by hand, there is no feeling of electric shock, and the safety is obvious. [LTEX's unique design ensures that every 15mm of static electricity generated on the static bar can generate numerous positive and negative charges in a single instant. ELTEX static elimination devices can be used on production lines with speeds up to 1 000 meters per minute. And because of its excellent results, it is generally only possible to use a single static-free bar in a workshop to eliminate static electricity completely.

Second, the application of static elimination

A. Install a static elimination device on the feeder of a sheet-fed offset press.

Flat printing presses can cause “swampy” or “multiple” phenomenon when printing PVC and other films due to serious static electricity. ELTEX electrostatic ion spray heads and hair dryer static elimination rods have been well applied. And become the designated brand of Heidelberg / KBA / Mitsubishi Machine Factory.

B. The problem of “black ink” common in gravure printing can be solved by static elimination.

C. Elimination of static electricity at the winding position during web printing prevents dust collection and electric shock operators.
D. In the screen printing, electrostatic dust is used to remove dust and the printing effect is remarkable.
E. Elimination by static electricity on the in-mold labeling line prevents mechanical adsorption of 'open' or 'multiple' labels.
F. Blister pack static elimination. More examples are no longer listed)

Third, the use of static electricity

Electrostatic application can play a role in reducing equipment energy consumption and improving the effect in production.

1. Typical electrostatic use

A. Electrostatic Absorption - Bringing Quality to the Web

Electrostatic ink-absorption system has been widely used in various gravure printing industries around the world, including packaging, decoration, books and magazines. Among them, the most significant effect is the cigarette pack printing industry.

ELTEX is one of the few suppliers of paper and plastic in the world's electrostatic ink-absorption system and has obtained international explosion-proof certification.

B. Electrostatic humidification

In a commercial web offset printing process, the printed matter must be passed through a hot air heated oven to dry the ink. Because the machine runs at a high speed, the moisture in the paper does not have enough time for natural rejuvenation after the loss of the drying process, causing many sequelae. (After binding, the label will curl, wave, etc.). ELTEX electrostatic humidification system can effectively and timely replenish the lost moisture after the paper passes through the oven.

2. Other use of static electricity

A. Static electricity is applied to adsorb the in-mold label.
B. Static electricity is applied to the stationary envelope on the binding machine.
C, the use of static electricity for the conveyor conveyor.
D Electrostatic application for die cutting machine

German ELTCX company was founded in 1933 and has a history of 51 years. Questions about the electrostatic treatment are welcome to discuss together, ELTEX company has many years of accumulated experience and continuous innovation for you to find the answer.