Electrostatic charges can cause problems when molten plastic parisons fall toward an open mold, for example, when there is more than one parison per blow mould, the static charge is always of the same polarity. Such parisons will repel each other, in which case it is usually impossible to transfer the object into the tool, and the pressure line on the blow moulded product will also cause quality problems; Similar problems can also arise when the metal parts of the machine are adsorbed.
Any matter is composed of atoms, and the basic structure of atoms is protons, neutrons and electrons. Scientists define protons as positively charged, neutrons as uncharged, and electrons as negatively charged. Under normal conditions, the number of protons in an atom is the same as the number of electrons, and the positive and negative charges are in balance, so it appears uncharged to the outside. However, due to external effects such as friction or in the form of various energies such as kinetic energy, potential energy, thermal energy, chemical energy, etc., the positive and negative charges of atoms will be unbalanced.
The friction mentioned in daily life is essentially a process of constant contact and separation. In some cases, static electricity can be generated without friction, such as inductive electrostatic electrification, pyroelectric and piezoelectric electrification, Helmholtz layer, jet electrification, etc. Any two objects of different materials can generate static electricity as long as they are separated after contact, and flowing air can of course generate static electricity.
Plastic materials are processed and produced by blow molding, and processed by blow molding to make plastic semi-finished products or finished products. Since most plastic materials are poor conductors, they have good insulation properties. Therefore, it is very easy to generate static electricity during the production process due to handling, contact, separation, friction, collision, and intervention in electromagnetic induction occasions, and stay on the surface of the item for a long time, causing static electricity hazards after accumulating to a certain static voltage value. For static electricity problems in the plastics industry, there are usually the following methods.
(1) Chemical method: that is, adding an antistatic agent that has a hygroscopic effect and is harmless to the plastic to the plastic material to reduce the resistance of its surface. The type of antistatic agent selected according to the different types of plastics is used; whether it is ionic or non-ionic, it is a hygroscopic antistatic agent. After adding these additives, this type of material absorbs moisture in the air and reduces the surface resistance to achieve anti-static performance.
(2) Physical methods: Generally, the most commonly used anti-static measures are grounding and maintaining the temperature and humidity of the working environment. It is also possible to install some products specially designed to eliminate static electricity on jobs that are prone to static electricity to eliminate static electricity.
(3) Blow molding mold processing Installing static elimination equipment on plastic mechanical equipment such as high-speed blister molding machines, slitting machines, and blow molding processing machines can effectively eliminate high-voltage static electricity generated when plastic sheets are pulled at high speed, and prevent sheets from being damaged due to Electrostatic adsorption of dust in the air or mutual adsorption between sheets due to static electricity can effectively improve the product grade and quality of plastic sheets after production and processing.
(4) Install an electrostatic ion bar at the entrance of the plastic raw material of the plastic injection molding machine to eliminate the high-voltage static electricity generated by the raw material during the flow, so as to prevent the raw material from being agglomerated due to static electricity and piled up at the entrance to directly affect production.