Resolving the technical problems of biting color in 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 shrink holes; 8 transfer without ink; 9 bite color (commonly known as cross-color) and fade; 10 gloss difference (white). These printing technology problems have become a commonly agreed production failure.

1. bite color (commonly known as string color). In the packaging printing process, when the first pass or the second pass of the color printing, the previous printing ink film surface will be found that the printing ink film is too soft, and even wrinkles, this phenomenon is called the prelude to bite. When the ink system contains a strong solvent at the time of printing (overprinting), it may completely penetrate the upper ink film and be bitten, and thus may be miscible in the latter color ink film. In severe cases, it may cause later packaging. The printed ink film is mixed with noise (dyeing). The main reason is that the printing ink contains soluble components (resin or solvent).

When printing on such inks, dilution solvents must be used. Do not use strong solvents to adjust the viscosity of the inks or speed up the printing process to shorten the time between two or three times. Use a mixed solvent to adjust the ink before printing. Solubility) effect to determine the proportion of diluted solvent.

2. Bad gloss (whitening). Most of these failures occur in the printing of volatile drying type printing inks, and an opaque white ink film layer appears during the rapid evaporation of solvents after high-speed printing. This phenomenon is sometimes temporary, but it is mostly persistent. This is due to the fact that the cooling device in the vicinity of the drying printing ink film is blown or the air is frozen to the dew point, that is, the absorbed water (vapor) is returned to the ink film and then condenses. If the solvent or pigment in the ink system contains water, it can also cause poor luster of printed ink film. That is, the higher the volatility of the solvent, the greater the tendency for the graphic ink film (whitening) luster of the packaging printing ink to be poor.

The preventive measures are : Adjust the solvents used for packaging printing inks; Increase the amount of high-boiling solvents (such as cyclohexanone, diols, propylene glycol ethers, butanol, etc.), reduce the amount of volatile solvents, and control the workshop during the packaging and printing process. The relative temperature in the environment (air) is below 65%, especially during the rainy season in the coastal areas and the rainy days in the north.