The problem of discoloration in the process of carton printing may be caused by a variety of factors such as ink, printing equipment, paper, etc., the following is a small series of Liaobu carton factory to tell you some common discoloration problems and solutions:
Discoloration caused by ink drying
Problem manifestation: The color changes during the drying process of the ink after printing, usually the color becomes darker or lighter.
Cause analysis: the ink drying speed is too fast or too slow, resulting in uneven distribution of pigment particles in the ink; The temperature and humidity of the drying environment are not suitable, which affects the drying effect of the ink.
Solution: According to the printing environment and paper characteristics, select the ink with the appropriate drying speed; Control the temperature and humidity of the dry environment, the general temperature is 20°C – 25°C, and the humidity is 50% – 60%; For inks that dry too fast, slow drying agent can be added appropriately, and vice versa.
Discoloration caused by the interaction of the ink with the paper
Problem performance: After printing, the color of the contact part between the ink and the paper changes, and there may be bleeding, fading and other phenomena.
Cause analysis: the pH of the paper is not suitable, and the chemical reaction with the ink occurs; The surface properties of the paper are poor, and the absorption is uneven, resulting in inconsistent ink penetration.
Solution: Detect the paper and select the paper with neutral pH or close to neutral; For paper with poor surface properties, pretreatment can be carried out first, such as coating moisture-proof agent or surface sizing treatment; Choose the right ink according to the absorbency of the paper, such as the high viscosity ink for the absorbent paper.
Discoloration caused by printing equipment
Problem manifestation: Deviation of printing color, or gradual change of color during the printing process.
Cause analysis: the ink roller of the printing equipment is worn or the pressure is uneven, resulting in uneven ink transmission; Improper installation or wear of the squeegee will affect the scraping effect of the ink.
Solution: Regularly inspect and replace the worn ink roller, adjust the pressure of the ink roller to make it uniform; Install the scraper correctly and replace the worn scraper in time; Perform regular maintenance and calibration of printing equipment to ensure the normal operation of the equipment.
Discoloration caused by changes in light sources
Problem manifestation: When observing the print under different light sources, the color will be different.
Reason analysis: the spectral distribution of different light sources is different, which will affect the color of the printed matter; Observe the unstable light conditions of the environment.
Solution: Observe the color of the print under a standard light source, such as a D65 light source (simulating daylight); Keep the light of the observed environment stable and avoid interference from other colors of light around you.
Discoloration caused by ink quality issues
Problem performance: the color of the ink itself is unstable, and the discoloration phenomenon occurs after printing.
Cause analysis: the pigment quality in the ink is poor, and the performance of light fastness and water resistance is poor; Ink deterioration due to excessive storage time or improper storage conditions.
Solution: Choose an ink with reliable quality and good brand reputation to ensure that the pigments in the ink have good stability; According to the storage requirements of ink, store the ink in a cool, dry and ventilated place, avoiding direct sunlight and high temperature environment; For inks that have been stored for too long, they should be tested and debugged before use.