Common troubleshooting methods of printing pearl film

1) Blocking phenomenon

　　 The gravure printing pearlescent film is prone to blockage, and the general performance is:

　　① Ink cannot be transferred in the light version; the amount of ink transfer in the dark version is reduced, usually from 50~70% to 30~20%.

　　 Reasons: In printing, with the large amount of solvent volatilization, the viscosity of the ink increases, the ink cannot enter the small dots, and the ink inside the cells gradually dry and cause serious blockage;

　　②In printing, the position of the squeegee is far away from the plate cylinder or the angle is unreasonable, the diameter of the plate cylinder is large or the depth of the plate cylinder into the ink tank is improper, causing serious blockage (the latter situation is common on domestic pearl film printing presses).

　　③The engraving depth of the screen line of the printing plate is not suitable, and the angle of the mesh is not suitable.

　　④ The ambient temperature during printing is too high, which makes the solvent volatilize too fast, causing blockage (prone to occur in summer).

　　⑤The ink itself is caused by reaction, especially the ink with the curing agent series. As the application time increases, the ink solidifies in the printing plate cells, gradually reducing the depth of the printing plate and causing blockage. This requires us to always check the blockage when using curing agent ink.

　　⑥ The ink formulation design is unreasonable, and a solvent with a high drying speed is used.

　2) Bite color

　　 Color biting phenomenon is that the ink printed in the previous color sticks back to the printing plate of the next color during overprinting, and the color of the previous color can be clearly seen on the next color. Reasons for biting color:

　　①The ink of the previous color is not sufficiently dried, and the drying speed of the next color is fast, causing the viscosity to increase instantaneously, and the previous color is stuck.

　　②The solubility of the resin in the ink is too good, which makes the ink easy to redissolve.

　　③The printing speed is too slow, so that the pattern parts of the printed film stay on the printing plate for a long time.

　　④The pressure of the impression cylinder of the latter color printing is too high.

Solutions to bite color:

　　①Use quick-drying solvent for the previous color to increase the drying rate of the previous color.

　　②Improve printing speed.

　　③Blow on the second color layout.

　　④Reduce printing pressure. Replace the ink.

solution:

　　①Adjust the drying speed of the ink, and use some slow-drying solvents according to the actual printing situation;

　　②Adding varnish to improve and increase the fluidity of the ink;

　　③ Clean the printing plate immediately after printing;

　　④According to the actual printing situation, add appropriate solvents in time to ensure that the printing viscosity of the ink is consistent;

　　⑤Redesign the ink formula to reduce the initial dryness of the ink and increase the fluidity and transfer performance of the ink;

　　⑥For the blockage caused by the use of curing agent, the following measures can only be adopted: do not add or as little curing agent as possible, and when it is necessary to increase, always pay attention to the occurrence of blockage during printing and clean up in time.