Traditional solvent-based coatings contain large amounts of volatile organic compounds, which cause serious pollution to the environment. As people’s awareness of environmental protection increases, traditional solvent-based coatings can no longer meet the requirements of increasingly stringent environmental regulations. Under this situation, light-curing coatings emerged and entered the public eye. Light-curing coatings have the characteristics of low organic volatile matter ( VOC ), environmental friendliness, fast curing speed, high production efficiency, high energy utilization, energy saving, and stable physical and chemical properties of cured products. The application of light-curing coatings has developed rapidly.
Photocurable coatings usually consist of photosensitive prepolymers, photoinitiators, reactive diluents and other additives. The most well-known to the public is UV curable coatings. Ultraviolet photocurable coating means that under the irradiation of ultraviolet rays, the photoinitiator in the liquid coating is stimulated to become free radicals or cations, thereby triggering a chemical reaction between the reactive substances ( Oligomer or Monomer ) in the coating, and finally Causes the formation of body structures, which cures the paint.
During the curing process of UV-curable coatings, the curing reaction is mostly carried out in an air atmosphere at room temperature. Oxygen in the air has an inhibitory effect on free radical polymerization. Therefore, it is necessary to overcome the inhibitory effect of oxygen and select a suitable photoinitiation system. Oxygen is further used to speed up the curing reaction. The inhibitory effect of oxygen comes from two aspects : first, its influence on the initiator system , which can quench the excited state photosensitizer and reduce the efficiency of photoinitiation ; second, it acts as a polymerization inhibitor during the polymerization process.
For this reason, the oxygen concentration has a direct impact on the light curing speed. By using inert gas to remove oxygen , the photocuring rates under different oxygen concentrations were compared. By adding active amine to overcome oxygen inhibition , the effect of different proportions of active amine components on overcoming oxygen inhibition was investigated . It was found that when 3% active amine was added , the curing speed increased by 2 to 3 times compared with the curing speed without treatment. Considering that the most direct cause of oxygen inhibition is the contact between oxygen in the air and the surface of the photosensitive coating. The Industry and Mining Network recommends using Ntron oxygen transmitter – SenzTX to detect oxygen concentration.
Ntron Oxygen Transmitter – SenzTX is a compact and rugged oxygen transmitter that utilizes zirconia or electrochemical technology to provide reliable measurement of oxygen concentration. Zirconia sensors respond quickly, have a long life and are drift-free ; while electrochemical sensors allow measurements in background gases containing hydrocarbons. For this purpose, the small range 0 to 10pp output can be used to monitor nitrogen production or oxygen in the glove box. Provide SenzTx transmitter range 0-96% 02 for medical oxygen concentrator. Multiple output options through process connectivity further increase instrument flexibility.
