Atmospheric Polymeric SiOx Thin Films Used in Printing Plates (Part 2)

Compared with the two methods, for the direct polymerization method in the plasma region, the deposition rate of the polymer on the substrate surface is slow, the film formation is not continuous, and the film formation is uniform by the plasma polymerization method in the downstream region of the plasma. The direct injection method is directly ionized when the monomer passes through the plasma zone, and then begins to deposit on the surface of the plasma gun wall and the internal electrode. At the same time, a strong electric field exists in the plasma zone, which also promotes the wall and the inside of the gun under the action of the electric field. Deposition on the electrode This deposition of monomers on the substrate is greatly reduced, thereby affecting the deposition rate and film formation. This was confirmed by the white powdery material found on the gun wall and internal electrodes after the experiment.

According to the comparative analysis of chemical bond energy, the bond energies of Si-O,C-O2 bonding modes are the largest, the products are most stable, the most favorable for bonding, and the si-zero bond already exists in the monomer, and the probability of recombination close to dissociation is close. Larger, and the C-0 key is easy to generate gaseous material and is lost, so it is more likely to generate Si-0. The experimental results of infrared spectroscopy also show that the product is mainly SiOx, with a certain amount of SiC, and a small amount of CO, CH, R, HOR and other compounds.

The DBD plasma gun was used to polymerize the SiOx film at atmospheric pressure. Two different injection methods were compared. The monomer input was introduced from the middle of the hollow inner electrode, and the sample was injected in the plasma downstream area and injected directly from the plasma area. The discharge characteristics and film-forming structure are not significantly different, and the film deposition rate is greatly improved. The ink-extraction experiment shows that the SiOx film polymerized with the plasma downstream area is good in ink repellency, and is obviously superior to the direct injection in the plasma area. Made a new waterless offset plate.

Authors / Han Erli 1, Chen Qiang 1, Zhang Guangqiu 1, Wu Changping 2
(1. Beijing Institute of Graphic Communication; 2. China Institute of Atomic Energy,

Source: Packaging Engineering, 4th Issue, 2005