How to Effectively Eliminate Static Electricity In Flexible Packaging Production?

The installation of anti-static brushes, static ropes, static eliminators, and control of workshop temperature and humidity in the process are all physical methods for eliminating and treating static electricity, which utilize the inherent characteristics of static electricity without changing the material properties.

In addition to physical methods, there are also chemical methods for eliminating static electricity.

Chemical electrostatic elimination method refers to the use of chemical additives, such as adding (filling) anti-static agents or coating techniques to modify the anti-static performance of resins, films, inks, etc. It is a more thorough and perfect method of anti-static technology. The chemical electrostatic elimination method is called because the addition or coating of anti-static agents causes changes in the chemical composition of the material. The chemical electrostatic elimination method is widely used in the packaging of electronic, food, pharmaceutical, cosmetic, chemical and other products (such as powder products mentioned earlier). While solving the anti-static performance, attention should be paid to the safety, hygiene, and compatibility with the matrix resin of the film.

1. Thin film anti-static masterbatch addition processing technology: Antistatic masterbatch is made by mixing anti-static agents with thermoplastic resins at a certain concentration (several percent to several tens of percent) and adding various additives. After melting, mixing, and granulation, anti-static masterbatch is produced. The selection of anti-static agents should pay attention to their compatibility with the matrix resin. If the compatibility is too poor, the anti-static masterbatch produced will have poor performance; If the compatibility is too good, the migration speed of the anti-static agent to the surface is too slow, making it difficult to form an anti-static film surface. The selection of matrix resin must be the same as the resin used in the processed product. During the process of melting, mixing, and granulation, the processing temperature should be kept as low as possible to prevent the decomposition or even deterioration of anti-static agents due to poor heat resistance, which may affect the anti-static performance of the mother material. The preparation of anti-static plastic films using anti-static masterbatch usually adopts a three-layer co extrusion blown film process. Pay attention to the proportion of anti-static masterbatch added in production, and determine it based on its effective concentration. Adjust it appropriately according to the test results to make its surface resistivity suitable. Excessive addition of anti-static masterbatch not only increases product costs, but also has adverse effects on the post-processing process.

2. Film anti-static coating treatment technology: Coating anti-static agent treatment technology is to make an anti-static coating from an ionic surfactant and apply it to the surface of plastic films to prevent charge accumulation. The selection of coating type anti-static agents should be determined based on the work function of the coated substrate. If the work function of plastic materials is large, they are prone to negative charges; If its work function is small, it is positively charged. In common plastic materials, work functions PP and PE are prone to negative charges, and cationic surfactants should be used for coating; PET and PA are highly positively charged and should be coated with anionic surfactants. When coating, it is required that the surface wetting tension of the plastic film is greater than 38 dynes, and the anti-static coating has good film-forming properties, friction resistance, chemical corrosion resistance, and long-lasting effect.

3. The addition of isopropanol in ink: Due to its good conductivity and volatility, isopropanol has a wide range of applications in the field of anti-static. Isopropanol is inexpensive and has a wide range of applications. In addition to being a commonly used solvent for inks, it is also often used as an anti-static agent, stain remover, cleaning agent, antifreeze, defoamer, etc. It should be noted that excessive isopropanol should not be added to the ink to avoid affecting the balance of the ink, and to avoid residual alcohol solvents affecting the composite performance.

4. The addition of anti-static agents in ink: During the ink production process, anti-static agents are added to prevent or eliminate static charges generated in the ink, and attention should be paid to the control of the amount added. Common antistatic agents include alkyl sulfonates, quaternary ammonium salts, and metal oxides. When using chemical methods to eliminate static electricity, please follow the correct operating steps and pay attention to safety. The process control method takes corresponding measures from the aspects of process flow, equipment structure, material selection, and operation management to limit the generation of current or control the accumulation of static electricity, ensuring that the charge is controlled within a safe range. For example, the amount of static electricity generated by the flow of hazardous chemicals in pipelines is proportional to the square of the flow rate. Reducing the flow rate reduces friction and the generation of static electricity. Therefore, the transportation speed of solvents can be limited. The larger the pipe diameter, the slower the speed. Metal materials should be used as much as possible for equipment and pipelines, with minimal or no use of plastic pipes.

The effective treatment of static electricity, whether using physical elimination or chemical elimination methods, needs to be tailored to the actual situation and combined with various methods to truly effectively treat static electricity. The experience of treating static electricity can be summarized as the “1234” five word mnemonic of “1 ground, 2 devices, 3 agents, and 4 shielding”: 1. Relying on “ground” to effectively guide charges out through effective grounding to prevent static electricity is the most direct, effective, and cheapest static electricity prevention and control measure in the soft packaging industry. It is necessary to pay attention to the smoothness of the overall output of the grounded terminals – branch lines – main lines – electric piles; build reasonable and timely effective static piles to eliminate charges and ensure their reliability. 2. Choose various effective charge neutralizing equipment based on “equipment”. To control static electricity, such as using static eliminators, static brushes, static ropes, workshop humidifiers, etc. Attention should be paid to the selection of equipment in different situations. Needle shaped neutralizing rods cannot be used in printing composite to avoid static ignition. Only ion type neutralizing rods can be selected to eliminate static electricity on both sides. 3. By adding various anti-static agents, surfactants, etc. to materials and inks to balance the generation of electrostatic charges through the use of “agents”; For example, the addition of anti-static agents and isopropanol in ink, as well as the addition of anti-static masterbatch in films, it is important to pay attention to the effectiveness and control of the amount of anti-static agents added. 4. The precision electronics industry places great emphasis on electrostatic shielding, which is relatively less commonly used in flexible packaging. Electronic product packaging related to the flexible packaging industry mostly uses electrostatic shielding bags, which are usually made of aluminum foil material and anti-static coatings for production. Thirdly, due to the invisible and intangible nature of static electricity, it can only be perceived when measuring charges or electric shock problems occur. At the micro level, static electricity constantly affects our ink and film. Static electricity can have an impact on ink supply, ink transfer systems, printing and drying systems, resulting in quality issues such as missed prints, ink whiskers, ink spots, pinholes, ink dots, and meteor lines during printing. Problems can all be caused by static electricity. In summary, the chemical composition, molecular structure, mechanical properties, smoothness, charge and electrical energy, environmental temperature and humidity, contact pressure, and friction separation speed of materials used by flexible packaging enterprises are all related to the factors that generate static electricity. At the same time, the time and voltage of electrostatic discharge vary depending on the type, contact method, contact time, contact area, and separation speed of the film used. Only by establishing an effective electrostatic prevention and control system tailored to local conditions can various quality problems in production be eliminated, production efficiency be effectively improved, and safety hazards be reduced. It should be clearly recognized that anti-static measures should be systematic and comprehensive, otherwise it may result in twice the result and even have a counterproductive effect. Only by deeply understanding static electricity and mastering the basic laws of static electricity generation can we as flexible packaging personnel effectively manage static electricity in practical operations, bringing economic benefits and long-term stability to the enterprise