The curing of the ink film when it passes through the curing unit once is very important. Proper curing can avoid the deformation, over curing, rewetting and under curing of the substrate to the greatest extent, and optimize the viscosity between ink and humor or between coatings. Screen printing factory must determine production parameters before production. In order to test the curing efficiency of UV ink, we can first start printing at the low speed allowed by the substrate, and then cure the printed sample. Then, set the power of the curing lamp to the value specified by the ink manufacturer. When dealing with colors that are not easy to cure, such as black and white, we can also appropriately adjust the parameters of the curing lamp. After the printing sheet cools, we can use the two-way hatching method to measure the adhesion of the ink film. If the sample sheet can pass the test successfully, the conveying speed of the paper can be increased by 10 feet per minute, and then printing and testing can be carried out until the ink film loses its adhesion to the substrate, and the conveying belt speed and curing lamp parameters at this time can be recorded. Then, according to the characteristics of the ink system or the suggestions of the ink supplier, the speed of the conveyor belt can be reduced by 20-30%.
1. If the colors do not overlap, should I care about the problem of excessive curing? When the surface of an ink film absorbs too much ultraviolet light, there will be a problem of over curing. If this problem cannot be found and solved in time, the surface of the ink film will become harder and harder. Of course, as long as we don't do color overprinting, we don't have to pay too much attention to this problem. However, we need to consider another important factor, which is the printed film or substrate. Ultraviolet light can affect the surface of most substrates and some plastics that are sensitive to ultraviolet light at specific wavelengths. This sensitivity to specific wavelengths coupled with oxygen in the air may lead to the degradation of the plastic surface. The molecular bonds on the surface of the substrate may be destroyed, which may lead to the failure of the adhesion between the UV ink and the substrate. The degradation of substrate surface function is a step-by-step process, and has a direct relationship with the ultraviolet energy it receives.
2. Is UV ink green ink? Why? Compared with solvent based ink, UV ink is indeed more environmentally friendly. The UV curable ink can become 100% solid, which means that all components in the ink will become a z-terminal ink film. The solvent based ink will discharge the solvent into the atmosphere as the ink film dries. Since solvents are volatile organic compounds, they may cause harm to the environment.