Curing judgment of UV ink in screen printing
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In screen printing, UV ink has become more and more widely used due to its high efficiency and pollution-free advantages. It will become a trend. When it comes to how to determine whether the ink is completely cured, many people think that it is used on the surface of the cured ink. The nails are scratched. But because each person's hand strength is different, the force method and angle are different; nail file is not a recognized standard, so this method is not scientific, there are many varieties of UV ink, the application range is different and the thickness difference depends only on It is impossible to determine whether it is completely cured by handcuffs. After several trials, the following methods are available for reference:
1. Test with pencil hardness
All the technical conditions for UV ink use pencil hardness. According to this requirement, we can test with a pencil hardness tester. If it meets the requirements (usually 3~4h), it proves that the ink has completely cured.
2. Test with the method of dropping solvent
As mentioned above, there are also solvent-resistant items in the technical conditions of the UV ink. After the propionic acid solution is dropped on the surface of the board for 2 minutes according to the solvent resistance, it is completely cured if there is no change. Since the internal molecular structure changes after the ink is completely cured, the conversion to the double bond is completed, and the high curing is completed, and the ink as a whole forms a tight coating layer.
3. Pressure test
This method is derived from the detection method of the coating. Use a 500g weight with a flat bottom surface, put a few cotton fibers on the UV-cured surface, press the weight on the cotton fiber for 2~3min, then remove the weight if the cotton fiber does not stick to the surface. Prove that the surface is fully cured.
4. Appearance observation method
The fully cured UV ink has a shiny surface with no illusion and no ghosting on the edges, which is one of the important features for determining the complete cure of the ink.
Of course, many of the experience gained through long-term production through the results of UV ink performance, working environment, working conditions, equipment performance synthesis and application is a valuable technical asset, but in today's technological development, how to make valuable The combination of experience and science will become the development direction of the industry. Combining the usual experience with testing to determine if it is fully cured will be more accurate.