Discoloration and floating white faults in packaging printing

Major technical problems in packaging and printing have long plagued people. The problems are mainly focused on 1 ink migration; 2 ink film yellowing; 3 white spots on printed products; 4 back sticking and adhesion; 5 discoloration and fading; 6 ink film floating white; Pin holes and shrinkage holes; 8 transfer without ink; 9 bite color (commonly known as cross-color) and fade; 10 gloss difference (whitening), these printing technology problems have become a common consensus of production failure.

1. Discoloration of printed products. Discoloration of ink film in packaging and printing is a failure in the printing process or in the outdoor aging stage of finished products. The printing ink film undergoes aging in the atmosphere. Under very severe conditions, premature discoloration or even discoloration occurs. The ink film is exposed in the atmosphere. Due to the effect of ultraviolet rays, the degree of color change depends on the temperature, temperature, and light of the atmosphere. The strength and the nature of the printing ink film, the saturation of the color and the tinting power of the color printing and the pH 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 our best not to use fading lake ink, and use rutile to extract white ink produced from titanium dioxide; add X24 to packaging printing ink to improve its anti-tarnish properties. At the same time adding brighteners is one of the common methods.

2. Ink film floating white. After the white ink and blue ink system is printed, the surface of the wet ink film exhibits irregular white pigment white spots (also known as floating colors, which are different from black and blue floating white spots), especially when compounded or After the aluminum plating will be more obvious exposure. If it is a blue ink, different sizes of pinhole-like blank spots tend to appear after printing, which seriously affects the appearance quality of the packaging print. The main cause of the failure is related to the type of pigment selected in the ink system, and the flocculation or separation of the pigment due to the incorporation of another ink, which causes the pigment in the ink system to float.

The countermeasures for this fault are: use pigments with the same particle size and the same specific gravity as raw materials, and the production of ink is better, and the second is to extend the dispersion time, or to subtract the additives containing the activity.