1. Prints change color
The discoloration of the printed graphic ink film is a failure that occurs during the outdoor aging stage of the printing process or the finished product. The printing ink film has been aged in the atmosphere, and under very harsh conditions, it has faded or even changed prematurely. The ink film is exposed to the atmosphere. Due to the effect of ultraviolet rays, the degree of color change varies with the temperature of the atmosphere, the temperature, the light of the sunlight The intensity and the nature of the printing ink film, the color saturation and coloring power of the color printing and the PH value of the ink film, the impurities in the atmosphere, or the length of the continuous exposure time in the atmosphere vary.
Therefore, before printing, we should try not to use the faded lake ink, but use the white ink produced by rutile refining titanium dioxide; add X24 to the packaging printing ink to improve its resistance to discoloration. Adding a brightener at the same time is also one of the common methods.
2. Ink film floating white
After printing and processing of white ink and blue ink system, the surface of wet ink film shows irregular white spots of white pigment (also known as floating color, which is different from black and blue floating white spots), especially when compound or It will be more obvious after aluminum plating. If it is blue ink, blank spots like pinholes of different sizes will often appear after printing, which seriously affects the appearance quality of the packaging printed matter. The main reason for this failure is related to the type of pigment used in the ink system, and there is also flocculation or separation of the pigment caused by mixing with another ink, which causes the pigment to float in the ink system.
The countermeasures for this failure are: use pigments with the same particle size and the same specific gravity as raw materials, and it is better to produce ink for gift printing. Second, extend the dispersion time, or subtract the additives containing activity.
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