Printed sign products that used for metal logo sticker, electroform nickel sticker, metal foils and other materials as substrates are called metal sign printing. In the process of metal sign printing, it is often encountered that there is a color difference in the printed matter. The following is a brief introduction to the control method of chromatic aberration in the process of metal printing signs:
In the process of metal sign printing, the color difference of the printed product mainly includes: ink solid color difference, overlapping color difference, dot deformation color difference, the color difference caused by inaccurate overprinting, color difference caused by abnormal wetting system, color sign printing and glazing production process. chromatic aberration, etc.
1. The color difference of the ink: such as primary color or spot color ink, the main reasons for the color difference of the solid background are: 1. The color and hue are not accurate, the type and proportion of the selected ink are unreasonable, and they cannot meet the printing requirements; 2. The printing properties of the ink are different from The performance of the printing machine and the drying room is not suitable; ③ The ink hue and the thickness of the ink layer are not suitable or the amount of ink is large.
Control methods: ① Collect data during the actual printing process of metal signs, clarify the relationship between the thickness of the ink layer and the solid density, and control the amount of ink during printing; ② The printing suitability of the ink should meet the objective conditions of printing, and the viscosity of the ink should be, The fluidity should be adjusted according to the nature of the substrate, the speed of the machine, and the type of graphics and text. The machine speed is fast and the solid printing is required. The viscosity of the ink is relatively small and the fluidity is relatively large, and vice versa; ③ When the ink is prepared for the first time, the printing sample should be used as the standard. standard basis.
2. Overlay chromatic aberration: including network lines and solid bottom, the main reasons for the overlaid chromatic aberration are: ①The color sequence arrangement is unreasonable; ②The ink viscosity is unstable.
Control methods: ① Control the thickness of the ink layer and the viscosity of the ink; ② Arrange the printing order of the metal signs reasonably: generally, the secondary color tone is printed first, and the main color tone is printed later. The color with low dot coverage is printed first, the color with high dot coverage is printed later, the anilox version is printed first, and the solid plate is printed later. The ink with high viscosity is printed first, the dark color is printed first, and the light color is printed later. The ones with a small image and text area are printed first, and the ones with a large image and text area are printed later. The darker ones are printed first, and the brighter ones are printed later. In fact, it is necessary to adjust the color sequence according to different contents and characteristics; ③ adjust the ink fountain and water fountain, and control the ink balance.
3. Dot deformation chromatic aberration: The main reasons for dot deformation chromatic aberration are: ①The increase or reduction of mechanical dots, including the influence of printing pressure, ink, fountain solution, blanket, metal plate surface coating, etc.; ②The increase of optical dots Or shrinking, which refers to the change of dots in the process of transferring the printed negative of the metal sign to the PS version.
Control methods: ① Adjust the pressure to meet the printing requirements. If the pressure is too large, the metal plate will expand in graphics and text, and if the dot imprint level is unclear, it will cause the plate to drop, which will affect the printing durability. If the pressure is too small, the printing plate has poor inking, poor imprint definition, and empty dots; ② Control the viscosity of the ink; ③ Control the pH value and conductivity value of the fountain solution; ④ The installation of the blanket meets the standards to prevent the blanket from stretching, Dot changes caused by torsion or compression deformation; ⑤Precise control of exposure time to ensure the restoration of negatives.
4. The color difference caused by inaccurate overprinting is mainly caused by the inaccurate positioning of each color version during the overprinting process.
Control methods: ①The pressure adjustment meets the requirements of metal sign printing, including various pads; ②The front gauge, side gauge, and gripper are positioned accurately; ③The installation of the PS version conforms to the regulations; ④The print size restores the film size; Accurate positioning; ⑥ The dimensional accuracy of metal sign production conforms to national standards and equipment performance.
