The characteristics and troubleshooting of cigarette labeling printing process (II)

When arranging the print sequence, the matte ink should be arranged in the last color. Such as the printing of a white, red, pattern hot stamping and matte effect of the smoke, the general color sequence is, first printed white, red ink, and then hot stamping, and finally printing matte ink. Because the matte ink is colorless and transparent, it can be printed on the surface of gold and silver cardboard and can transmit the inherent metallic luster of the printing material to achieve the printing effect of imitation metal etching. Moreover, the last printed frosted ink can also reveal the color of the ink printed the previous time.
(5) Curing method

Cured with a high-pressure mercury lamp. The lamp life is generally 1500 to 2000 hours and requires frequent replacement. The price of homemade lamps is about 1,000 yuan each; the price of imported lamps is between 3,000 and 4,000 yuan.

(6) Printing pressure

When printing matte ink, the pressure of the squeegee should be slightly larger than that of the ordinary color ink, and the pressure should be kept consistent.

(7) Printing speed

The particles of the matte ink are relatively large. To make the matte ink fully penetrate the mesh, the printing speed should be lower than that of other inks. In general, the printing speed of other inks is 2500±100 sheets/hour; the printing speed of matte inks is generally 2300±100 sheets/hour.

(8) Screen Requirements

Generally, the imported plain nylon net of about 300 mesh is used, and the tension of the stretch net is even. In the printing process, the deformation of the print plate is also strictly controlled.

5. Common faults and solutions

(1) poor metal texture

Causes: The thinner added to the ink is not suitable; the power of the UV lamp is insufficient; the quality of the printed material is poor.

Solution: Add a diluent matching the matte ink before printing; the amount of diluent is accurate and the stirring is adequate. During the curing process, the power range of the light source should be selected according to the thickness of the ink layer and the speed of the light beam traveler. The power of the light source should be 0.08-0.4 kW. In addition, it is also necessary to choose a substrate with a higher metallic luster, with no scratches on the surface and suitable tensile strength and high temperature resistance.

(2) The roughness of the matte surface and uneven distribution of particles

Cause: Printing pressure is inconsistent.

Solution: The length of the scraper should be slightly larger than the width of the printing substrate. Smoke label printing can choose right angle scraper, but the hardness of the glue scrap should not be too high, the general hardness is HS65.

(3) Ink dry on screen

Cause: Natural light shines on the screen. Because the natural light contains a large amount of ultraviolet ray, it is easy to cause the photosensitizer in the ink to cure. Paper surface or ink contains impurities.

Solution: Try to avoid natural light direct printing plate; use high surface strength paper; printing environment should be kept clean.

(4) Adhesion of printed matter

Cause: The ink on the print is not completely cured.

Solution: Improve the power of the light curing machine; reduce the speed of the light curing machine; reduce the ink layer thickness on the premise of meeting the printing requirements.

(5) Sticky

Cause: The paper is not positioned correctly and the impression cylinder gripper is improperly adjusted.

Solution: Calibrate the paper positioning system and adjust the position of the grippers to prevent the paper from rotating with the rollers.

(6) Cracked Plate

Cause: The printing pressure is too high and the tension of the stretch net is uneven.

Solution: Adjust the pressure of the squeegee evenly; maintain the tension of the stretch net evenly; it is better to choose the imported net cloth.

(7) Figure hairy

Cause: ink viscosity is too large.

Solution: Add appropriate diluent to adjust the viscosity of the ink; avoid ink drawing.