Introduction of plasma suface treatment technique
Plasma treatment is one of the effective surface cleaning, activation, and coating processes, which can be used to treat various materials, including plastics, metal, or glass.
Fundamental theory
The temperature of neutral particles is close to room temperature, which provides suitable conditions for surface modification of thermosensitive polymer. Through low-temperature plasma surface treatment, there are many physical and chemical changes on the surface of the material, such as etching and rough, forming a dense cross-linking layer, or introducing oxygen-containing polar groups to improve the hydrophilicity, cohesiveness, dyeability, biocompatibility, and electrical properties.
Surface treatment of plastics by plasma technology
The energy of particles in the plasma is generally about several to dozens of electron volts, which is greater than the binding bond energy of polymer materials (several to ten electron volts), which can completely break the chemical bonds of organic macromolecules and form new bonds; however, it is far lower than that of high-energy radioactive rays, which only involves the surface of materials and does not affect the performance of the matrix. In the non-thermodynamic equilibrium state of low-temperature plasma, electrons have higher energy, which can break the chemical bond of the surface molecules of materials and improve the chemical reaction activity of particles (higher than that of thermal plasma), while the temperature of neutral particles is close to room temperature. These advantages provide suitable conditions for surface modification of heat-sensitive polymer.
Advantage of plasma treatment
1、The surface treatment depth of the box is small but very uniform.
2、There is no paper scraps, which belongs to environmental protection treatment.
3、There is a certain distance between the plasma nozzle and the packaging box. Only by spraying the low-temperature plasma through the nozzle to the place where the packaging box needs to be coated, it can handle all kinds of complex shapes of packaging boxes, with continuous operation and stable product quality.
4、No other fuel is consumed in the work, and it can be operated only by connecting the common power supply, which greatly reduces the cost of packaging and printing.
The plasma surface processor has developed several models, such as single nozzle, double nozzle, three nozzles, rotary nozzle, etc., which ejects low-temperature plasma, and its shape is like a flame, but it will not ignite the packaging box. For the convenience of users, the plasma surface processor also has the function of safety interlock. The user can install the automatic control device in the production line according to the needs. Once there is no packing box in the production line, the plasma surface treatment machine will automatically stop spraying plasma, and when there is a package box passing by, it will automatically eject plasma There is also a vacuum plasma processor. Electrodes are set in a sealed cabin. Under the action of a vacuum pump, the air pressure in the cabin reaches 5-10 millitorrs. Under the action of a high-frequency generator, plasma is generated between the electrodes, and then the surface of the sample is treated to achieve the purpose of modifying the surface activity.