Abstract Low-temperature plasma technology has good surface treatment uniformity when processing organic materials, which can greatly improve the surface energy of the substrate, and has good application prospects in ink printing, hydrogel coating, and vacuum aluminum plating machine.
Plasma is an ionized gas composed of a large number of free electrons and ions, and appears to be approximately electrically neutral on a macro scale. It is an aggregated state of matter: the plasma state, also known as the fourth state of matter.
The electrons in the low-temperature plasma obtain energy from the electric field and become free high-energy electrons. They collide with atoms and molecules in the gas to generate excitation and ionization phenomena. The excited molecules, atoms, ions, and free radicals generated from them are extremely unstable. , Has a high chemical reactivity, it is easy to occur reactions that cannot be generated under normal circumstances, and generate new compounds.
When processing the surface of a thin film such as a PP film, in the plasma state, the ionized gas reacts with the surface of the material, such as activation, grafting, deposition, polymerization, etc., so that the composition of the surface of the material changes, resulting in surface properties. obvious changes. Such as material surface hydrophilization treatment.
Low-temperature plasmas are very different from ordinary gases in nature. The temperature of the electrons in the low-temperature plasma can reach thousands to tens of thousands of K, while the gas temperature is very low, about room temperature to hundreds of degrees Celsius, and the electron energy is about several to a dozen electron volts. This energy is greater than the bond energy of the polymer material (a few to a dozen electron volts), which can completely break the chemical bonds of organic macromolecules to form new bonds; but it is far lower than high-energy rays and only involves the surface of the material, so it does not affect the matrix Performance. These advantages provide suitable conditions for the surface modification of heat-sensitive polymer materials.
Low temperature plasma technology has the following advantages in processing organic materials:
① Plasma technology is a dry process, which is energy-saving and pollution-free, and meets the needs of energy conservation and environmental protection;
② Short processing time and high efficiency;
③ There are no strict requirements on the materials processed, and it is universal;
④ Can handle materials with complex shapes, and the surface uniformity of the material is good;
⑤ The processing temperature is low;
⑥ The effect on the surface of the material only involves a few to several hundred nanometers, which will only improve the surface properties of the material without affecting the substrate properties.
The One Atmosphere Uniform Glow Discharge Plasma device developed by Nanjing Suman Electronics Co., Ltd. can generate plasma quasi-glow discharge without using low-pressure environment and without helium environment. The advanced technology level fills the blank of the domestic plasma quasi-glow discharge technology at low temperature and normal pressure.
The following is the application of plasma quasi-glow discharge technology at low temperature and normal pressure.
Application in coating and printing: As the water content increases, the surface tension of the water-based coating will increase, which requires the surface energy of the coated substrate to be correspondingly increased, otherwise it will cause shrinkage pores after coating and the combination of the coating and the substrate. Disadvantages such as decreased power and easy fall off. Corona is commonly used to increase the surface energy of substrates. However, corona treatment can only improve the surface energy of film substrates such as PET to about 45 dyne, and the barrier properties of the material will decrease, the material will become brittle, and the mechanical properties will decrease. Utilizing a low-temperature plasma quasi-glow discharge device under normal pressure, the surface energy of the material after treatment can reach more than 72 dyne, and the discharge is uniform, and the performance of the substrate will not cause a large impact, making water-based coating and ink printing easier , Especially for products with thin coatings (such as several micron coatings) and high uniformity requirements.
Application on vacuum aluminizing machine: The substrate before the aluminizing on the vacuum aluminizing machine is treated with plasma quasi-glow discharge, which improves the surface energy of the substrate, and the surface energy uniformity is better than that of corona treatment. Higher level. In this way, after aluminizing substrates such as CPP, BOPP, PET, the aluminum layer and the substrate have higher fastness and uniformity, and the brightness and barrier properties of the aluminized film will be better. The author believes that if domestic vacuum aluminum plating machines are replaced by corona treatment with plasma quasi-glow discharge treatment, the product quality will be improved, and the gap with imported machines will be reduced (at present, international advanced vacuum aluminum plating machines are equipped with plasma processing devices) .