1. Inaccurate color matching
(1) Film tension changes, resulting in longitudinal printing register changes. The tension control devices should be adjusted, such as adjusting the reel brake of the unwinding device, reasonably setting the rotation speed of the roller, increasing the friction force of the roller surface, adjusting the coiling tension of the rewinder, etc.
(2) There is a diameter difference in the printing cylinder. The diameter of the first, second and third color printing plate cylinder increases or decreases in turn, which causes the change of vertical printing register. A new plate should be made.
(3) Regular line density is insufficient, printing register longitudinal offset. The sensitivity of the photocell should be adjusted and the paste fault of the printing plate should be eliminated.
(4) The problems such as non parallel guide roller, uneven printing pressure and taper of plate cylinder and press cylinder lead to film lateral swing, unilateral relaxation and instability of lateral register. It should be adjusted accordingly.
(5) The adjustment screw at the shaft end of plate cylinder is loose, which causes the instability of horizontal register. The tightness of the screw should be readjusted.
(6) If the contact pressure between top roller and flower roller is too high, the printing pattern will produce double pattern. Therefore, the contact pressure should be adjusted to make the printed pattern clear.
2. Pattern distortion
(1) The film shrinkage allowance is insufficient, and the pattern size shrinks along the longitudinal direction during printing. In the printing process, due to the influence of film tension and heating and drying factors, the film will shrink along the longitudinal direction. Therefore, enough shrinkage should be reserved when making layout, and the tension of film should be reduced as much as possible.
(2) Too much shrinkage allowance is reserved in the film, and the pattern is elongated and deformed along the longitudinal direction during printing. Therefore, the film tension should be increased.
3. The reproducibility of pattern level is poor
(1) Because the printing plate is too deep, the highlight (bright part) is too deep. Should increase the mesh, reduce the proportion of pigment in the ink, or try to scrape the blade up and force again.
(2) The depth of the plate is not enough, so that the highlight is too shallow. Should use a dark color ink, or try to tilt the blade, scraping lighter.
(3) Plate corrosion is too deep, so that the dark (dark) is too deep. Should be re plate, otherwise, the ink is not easy to dry.
(4) Plate corrosion depth is not enough, so that the dark spot density is not enough. You should switch to dark color ink.
(5) Poor ink printing performance, so that the intermediate tone (with light and dark) ink depth at the junction of poor flow. Ink with better printing characteristics should be used.
4. There are spots on the printed surface
(1) Ink viscosity is too low or poor flow. The viscosity of the ink should be properly adjusted to make the viscosity of the ink moderate and good fluidity.
(2) Plate depth is too deep or blade angle adjustment is improper. The angle of scraper should be adjusted properly, or plate making again.
(3) Improper control of printing pressure. It should be adjusted appropriately.
(4) There is too much static electricity on the surface of printed matter. Static electricity should be eliminated.
(5) Poor ink drying. Drying should be strengthened, such as improving ventilation and drying conditions.
5. The pattern is not clear
(1) The ink layer is too thick. Should reduce the amount of ink.
(2) The solvent in the ink volatilizes too fast. The type and amount of solvent should be adjusted to reduce the volatilization rate of solvent.
(3) The plate mesh is blocked. Mesh should be cleaned.
(4) When drying, the wind speed is too high, resulting in drying too fast. The wind speed should be properly reduced to slow down the drying speed.
(5) The distance between the scraper and the plate is too large. The distance between them should be adjusted properly.

(6) The printing plate pattern is too shallow or uneven. Use dark ink or change the mesh.

6. Blistering on printing surface
(1) If the surface of the ink has been crusted, and the internal ink is not dry, once the crust is broken, the volcanic vent like bubbles will be formed, which is mainly due to rapid drying. Should adopt low temperature - high temperature - low temperature drying process route, and try to use slow drying ink.
(2) In the process of printing, a large number of bubbles will be produced in the ink bucket, which will adhere to the printing roller and make the dot of the printed pattern disappear or stain the pattern. In this regard, should make the ink to maintain the appropriate viscosity, to minimize the ink drop, and the use of circulation pump, to prevent bubbles into the ink.
7. The printing surface has serrated apron
As the moisture in the air enters the ink, the resin is precipitated and gelatinization occurs, resulting in the decrease of the concentration of ink, the increase of viscosity, the decrease of gloss and the dot adhesion. In particular, pattern less, ink consumption less parts, often appear zigzag ring. In this regard, should try to use new ink, and use appropriate slow drying solvent.
8. There are pear peel patterns on the printing surface
If in the dry printing surface overprint, the background ink is dissolved and partially mixed with the second color ink, the printed surface will produce pear peel pattern. In this regard, the first is to adjust the ink viscosity; the second is to control the drying speed correctly; the third is to determine the depth of the plate reasonably.
9. Poor adhesion of ink
The way to judge whether the ink is not attached well is to stick the transparent tape on the printing surface and tear it off rapidly in the direction of 45 degrees to observe whether the ink is attached to the tape. The causes and Countermeasures of poor ink adhesion are as follows:
(1) Improper selection of ink type. That is to say, the resin used in the ink connection material does not conform to the material of the plastic film. Usually different substrates should choose different inks, and different inks can not be mixed.
(2) The surface treatment of plastic film is improper or the storage time after treatment is too long. The lubricant and plasticizer must be removed from the film surface.
(3) The drying temperature is too low and the heating is poor. Generally, the higher the dryer heating temperature, the better the ink adhesion, heating temperature is not enough, not only easy to produce bleaching and fading, but also more residual solvents, easy to produce poor ink adhesion. Therefore, when the ink adhesion is not good, should appropriately improve the drying temperature.
(4) Film moisture will reduce the adhesion of the ink. Therefore, we should pay attention to the storage conditions of the film and adjust the humidity of the printing environment.
(5) The film corona treatment is poor, and the surface static electricity is too high, resulting in the exudation of linear whiskers around the map line, or in the full printing area because of smooth and can not be printed, showing fuzzy spots, or ink completely can not be printed, showing a blank. For this reason, corona treatment should be carried out again or other remedial measures should be taken, such as increasing the environmental humidity, grounding the guide roller, and contacting the grounding metal immediately after the film leaves the printing roller.
10. Poor ink absorption
When the film surface of the product is multi-color printing, if the ink of the second color is printed on the film of one color, if the absorption is poor, the dot after the ink transfer will become an independent state one by one, forming the uneven phenomenon of darker dot color and lighter color of other parts. This has nothing to do with the transfer of ink or disharmony and other issues, mainly with the diffusion of dot ink after transfer. In this regard, the first is to use lagging solvent in the second color ink; the second is to make the second color ink scraper position move close to the printing direction as far as possible; third, the ink after the second color should be pressed as light as possible; the fourth is to appropriately deepen the plate depth of the second color; the fifth is to use reducing agent in the background ink; the sixth is to increase the printing speed appropriately.

11. Poor drying and adhesion of ink
(1) Improper adjustment of drying device. The drying process parameters such as air temperature, wind speed, air volume and exhaust volume should be adjusted properly.
(2) When using solvent evaporation drying ink, sometimes the ink surface has been dry, but there is still not volatile solvent inside, and slowly exudes, so that the film is bonded together. Therefore, the residual solvents should be determined by gas chromatography, so as to determine the operating conditions, such as solvent type, dosage and ink layer thickness.
(3) Plate corrosion is too deep, dark part of the ink pile is too thick. A new plate should be made.
(4) When printing soft PVC film, the plasticizer will migrate to the ink and soften the color carrier (resin) of the ink. To this end, should use a special formula of ink, otherwise, film printing after easy adhesion. In addition, the moisture in the film will also make the ink in the carrier wetting and adhesion. Therefore, moisture-proof film should be paid attention to in storage.
(5) When using two-liquid reactive ink, the curing agent can also make the surface of the impression wrinkle adhesion. Attention should be paid to adjust the ratio of the two solutions to avoid excess reaction.
(6) The printed film should be kept away from heat and direct sunlight; it is better to stack vertically and stagger.
12. Printing surface deinking or non inking
(1) The ink layer is too thick. It should be thinned properly.
(2) Ink is not easy to dry. The type and amount of solvent should be adjusted, the volatilization speed of solvent should be accelerated, and drying should be strengthened.
(3) The ink dries too fast to print. The type and amount of solvent should be adjusted to slow down the evaporation rate of solvent.
(4) The printing speed is too fast. It should be slowed down appropriately.
(5) The printing pressure of the next printing process is too high. The pressure of lining roller in the next process should be adjusted properly.
(6) The content of plasticizer in the film is too much, so that the film surface is not inked. The amount of plasticizer should be reduced. For the variety of plasticizer, dibutyl phthalate is generally suitable.
(7) Improper selection of ink varieties. Ink should be replaced.
13. Scratch on printing surface
(1) There is a gap in the blade of the scraper. The blade should be sharpened.
(2) There are hard particles in the ink. The ink should be ground to the required fineness.
(3) The ink is mixed with foreign matters and impurities. The scraper should be lifted to remove foreign matters and 80 mesh copper mesh should be used to filter the ink.
(4) The scraper is uneven or the installation angle between the scraper and the printing roller is not adjusted properly, and the ink can not be scraped clean. The blade should be ground and polished, and the installation angle of scraper and printing roller should be adjusted properly.
(5) Due to the uneven contact between the scraper and the printing roller or the surface of the printing roller is embedded with hard objects, the cutter jumps. The scraper should be leveled to make it flat on the surface of the printing roller, and the hard objects embedded in the surface of the printing roller should be removed.
14. Printing roller wear too fast
(1) The scraper is too thick. A thinner blade should be used.
(2) The contact pressure between the scraper and the printing roller is too high. The contact pressure should be adjusted properly.
15. The blades wear too fast
(1) The blade is too thin. A thicker blade should be used.
(2) The contact pressure between the blade and the printing roller is too large. The contact pressure should be adjusted properly.
16. Version screen blocked
(1) In the printing process, with a large amount of solvent volatilization, the ink viscosity increases, resulting in the ink drying and blocking inside the wire. Dry ink should be removed regularly.
(2) When the position of the scraper is far away from the printing roller, the diameter of the plate roller is large or the depth of the plate roller into the ink groove is not enough, the hot air blown out from the machine affects the ink on the surface of the roller, which is easy to cause serious blocking. In this regard, we should make targeted adjustments.
(3) Ink mixed with impurities caused by blocking. Impurities should be removed and ink should be filtered.
(4) In the printing process, the operating temperature is too high, which causes the solvent in the cylinder wire to evaporate too fast, resulting in the blocking of the screen. Try to reduce the operating temperature.
(5) The etching depth of plate roller wire is not suitable. A new plate should be made.
17. Printing discoloration