Static electricity generated on the surface of plastic may cause various problems, such as hindering production, sparks that cause explosions and damage to integrated circuits of electronic equipment, and the method of eliminating static electricity should be combined with the actual production, the purpose of the packaging material (what product to pack), and the customer’s use conditions. In other cases, adopt different antistatic technologies to eliminate static electricity.

1. Physical elimination method

The physical elimination method is a method of eliminating the static electricity itself without changing the properties of the material. For example, the “grounding” elimination method is to install antistatic brushes in the process. Place the brush body at the rewinding or unwinding place of the paper or plastic coil, and make the grounding end of the anti-static brush reliably ground, and cannot be connected to the equipment or the guide roller. Because the equipment may be poorly grounded; some guide rollers are anodized, and aluminum oxide is formed on the surface, and aluminum oxide is non-conductive. For example, the high-voltage discharge electrostatic elimination method uses a high-voltage discharge electrostatic eliminator to eliminate static electricity. The static eliminator is divided into unipolar and bipolar according to the discharge polarity. Unipolar ionizers neutralize only one charge (positive or negative), and bipolar ionizers neutralize both positive and negative charges. The environmental humidity control method is also a relatively common method. Increasing the relative humidity of the workshop environment (suitable in the range of 60% to 70%) can increase the moisture on the surface of plastics and paper to form a thin, conductive water film, thereby accelerating static electricity. leakage. The above three combined static elimination methods are more common in printing, compounding, slitting and bag making processes.

2. Chemical elimination method

The chemical elimination of static electricity is the antistatic agent treatment technology, which is mainly a method of modifying the electrical properties of the resin or substrate by adding (filling) technology or coating technology to the antistatic agent (surfactant). Perfect antistatic technology. However, due to the addition or coating of antistatic agents, the chemical composition of the material is changed, so this technology is not suitable for the treatment of paper, but only for the modification of plastic resins.

Especially in the packaging of food, medicine, cosmetics, chemical products, etc., attention should be paid to safety, hygiene and compatibility with the matrix resin, etc., so the technical content is high. Packaging materials with antistatic properties not only eliminate various quality accidents caused by static electricity, but also improve packaging efficiency for customers and ensure sealing strength, so they are recognized by customers. It is gratifying that the plastics industry has strengthened the research on antistatic agents as early as the early 1990s, the performance of antistatic agents has become more and more mature, and the treatment technology of antistatic agents has also been widely promoted and used.

Depending on the usage, there are two types of surface active antistatic agents, external and internal, topical, or topical antistatic agents are applied to the surface of the polymer by spraying, wiping, or dipping. Although this topical antistatic agent is suitable for a variety of polymers, its effect is only temporary, and it is easily lost after contact with solvents or friction with other objects. Internal antistatic agents are incorporated into the polymer during cnc machining. Such surface-active antistatic agents can supplement the antistatic function that is eroded by the handling process. The effect of this internal antistatic agent depends on the frosting. Blooming here means the process in which the internal antistatic agent added to the resin partially migrates to the polymer surface. Therefore, the internal antistatic agent has a long-term antistatic protection effect.

3. Additive Manufacturing technology

This technology (i.e. master batch technology) is to mix additive antistatic agent with thermoplastic resin at a certain concentration (several to tens of percent), and add various additives, and then melt, knead, and granulate. , to obtain antistatic masterbatch. The selection of antistatic agent should pay attention to the compatibility with the matrix resin. If the compatibility is too poor, the antistatic particles prepared will have poor performance; but 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 same resin as the product resin is used as the base resin. During the process of melting, kneading and granulation, the Additive Manufacturing temperature should be maintained as low as possible to prevent the antistatic agent from decomposing or even deteriorating due to poor thermal stability. Using antistatic particles to prepare antistatic plastic film, often using three layers (ABC)

Co-extrusion blow molding process. Note that the proportion of antistatic masterbatch added should be determined according to the concentration of its effective substances, and should be properly adjusted according to the test results, so that the surface resistivity ps is about 1011Ω; the increase in the amount of addition not only increases the cost of the product, but also affects the later stage. adversely affected by the cnc manufacturing steps. To prepare antistatic composite packaging materials, add antistatic particles to the functional surface (hot cover) instead of the composite surface (corona treated surface) to prevent the migrated antistatic agent and water film from forming a barrier layer and affecting the composite peel strength of the material. Antistatic masterbatch can also be added to coating grade resins such as PE and PP in a certain proportion through extrusion compounding (precision casting) process, thereby avoiding the quality problems caused by film adhesion and foreign matter adsorption.

4 coating type processing technology

The new coating type antistatic agent treatment technology is to make high molecular conductive polymer (PEDOT: PSS polythiophene), ITO, nanomaterials, etc. into antistatic coatings, which are coated on plastic products (PET, PVC, PP, PE, PC, etc.). etc.) surface, to prevent the accumulation of charges, so that the product achieves transparent conductive, anti-static effect, compared with the traditional coating type antistatic agent and other treatment methods, it has the advantages of environmental protection, transparency, stability, cleanliness and good conductivity. Antistatic coatings have good film formation, friction resistance, chemical corrosion resistance and long-lasting effect. The method of preparing the antistatic coating is as follows: dissolving the antistatic agent in an alcohol-soluble or ester-soluble resin or emulsion with good film-forming properties and firm adhesion to the plastic film; also using a polyurethane adhesive as a carrier and dissolving it with an ester; It can be dissolved in solvent-based plastic coatings to make antistatic coatings. When coating, pay attention to select the appropriate coating dry amount, set the drying oven step temperature, control the coiling speed and the relative humidity of the environment, and prevent haze, rainbow and other phenomena after coating.