There are many factors that affect the curing and drying of water-based UV inks. This article only discusses the main influencing factors. These factors are as follows:
1. The pre-drying of aqueous system has a great influence on photo-curing. When it is not dry or incomplete, the curing speed is slow, and with the prolongation of exposure time, the gelation rate has no obvious increase. This is because, although water has a certain effect on inhibiting the inhibition of oxygen, this only allows the ink film surface to rapidly solidify, and it only reaches the surface dryness, and it cannot reach the dry state. Because the system contains a large amount of water, when the system is cured at a certain temperature, the surface of the ink film rapidly solidifies as the moisture on the surface of the ink film rapidly evaporates, and the water inside the film layer is difficult to escape, and a large amount of water remains in the ink film. The ink film is prevented from further curing and the curing speed is reduced. In addition, the ambient temperature at the time of UV irradiation has a great influence on the curing of the UV ink. The higher the temperature, the better the curing. Therefore, if the preheating is performed, the curability of the ink will be enhanced and the adhesion will be better.
2. Effect of water-based UV curing resin on light curing
Water-based UV-curable resins undergo radical photo-curing. This requires that the resin molecules must have unsaturated groups. Under ultraviolet irradiation, the unsaturated groups in the molecules crosslink with each other, and the liquid coating becomes a solid coating. Floor. The method of introducing an acryloyl group, a methacryloyl group, a vinyl ether, or an allyl group is generally adopted so that the synthetic resin has an unsaturated group, so that it can be cured under suitable conditions. It is often used. For the radical-type UV curing system, as the content of the double bonds in the molecule increases, the crosslinking speed of the coating film increases and the curing speed increases. Also, resins of different structures have different effects on the curing speed, and the reactivity of various functional groups generally increases in the following order: vinyl ether <allyl <methacryloyl <acryloyl. Therefore, the introduction of acryloyl and methacryloyl groups is generally the main, so that the resin has a faster curing speed.
1. The pre-drying of aqueous system has a great influence on photo-curing. When it is not dry or incomplete, the curing speed is slow, and with the prolongation of exposure time, the gelation rate has no obvious increase. This is because, although water has a certain effect on inhibiting the inhibition of oxygen, this only allows the ink film surface to rapidly solidify, and it only reaches the surface dryness, and it cannot reach the dry state. Because the system contains a large amount of water, when the system is cured at a certain temperature, the surface of the ink film rapidly solidifies as the moisture on the surface of the ink film rapidly evaporates, and the water inside the film layer is difficult to escape, and a large amount of water remains in the ink film. The ink film is prevented from further curing and the curing speed is reduced. In addition, the ambient temperature at the time of UV irradiation has a great influence on the curing of the UV ink. The higher the temperature, the better the curing. Therefore, if the preheating is performed, the curability of the ink will be enhanced and the adhesion will be better.
2. Effect of water-based UV curing resin on light curing
Water-based UV-curable resins undergo radical photo-curing. This requires that the resin molecules must have unsaturated groups. Under ultraviolet irradiation, the unsaturated groups in the molecules crosslink with each other, and the liquid coating becomes a solid coating. Floor. The method of introducing an acryloyl group, a methacryloyl group, a vinyl ether, or an allyl group is generally adopted so that the synthetic resin has an unsaturated group, so that it can be cured under suitable conditions. It is often used. For the radical-type UV curing system, as the content of the double bonds in the molecule increases, the crosslinking speed of the coating film increases and the curing speed increases. Also, resins of different structures have different effects on the curing speed, and the reactivity of various functional groups generally increases in the following order: vinyl ether <allyl <methacryloyl <acryloyl. Therefore, the introduction of acryloyl and methacryloyl groups is generally the main, so that the resin has a faster curing speed.