Various problems often appear in the screen printing process, and the analysis of several common main problems is as follows:
① There is no ink on the surface of the substrate (that is, uneven ink leakage), the main reasons are:
a. The screen mesh number is too high, and the over-inking property is poor;
b. The photosensitive film is thicker and the over-inking property is poor;
c. There are scars on the edge of the scraper;
d. The impression force of the scraper is not enough, or the impression force is uneven;
e. The gap between the screen printing plate and the substrate is too large;
f. Ink viscosity is too high;
g . The ink returns to the scraper to send ink unevenly;
h. The printing speed is too fast, which makes the ink supply uneven;
②After printing, the ink seeps, and the pictures and texts are blurred; after the printing of the play, the edges of the pictures and texts have seeping and blurring, the main reason is that;
a. The edges and corners of the scraper blade are worn, and the effect of ink breaking in the scraper is poor;
b. The scraping angle of the scraper is too small, resulting in excessive ink supply;
c. Ink viscosity is too low. After printing, the ink flows and penetrates;
d. The ink and the solvent are not stirred evenly, and the ink with a lot of solvents after printing will cause seepage;
e. After the screen printing plate is cleaned, there is residual solvent;
f. Misalignment of the overprinting rules of the screen printing plate and the substrate;
g. Improper choice of oil plastic and wire mesh mesh. Ink particles are too low for finer screen days.
③Ink drawing and ink unevenness, the main reasons are:
a. The cutting property of the ink is not good;
b. The screen printing plate leaves the substrate slowly;
c. The screen printing plate has a small space around the graphic;
d. Drawing or ink unevenness caused by static electricity;
e. The scraping angle is too small;
f. Uneven printing speed.
④ Bubbles are generated after printing, the main reasons are:
a. The screen printing plate is not rinsed clean;
b. Dust mixed with ink to block the mesh;
c. Dust adheres to the screen printing plate or substrate.
⑤ The printing resistance of the screen printing plate is low, the main reason is:
a. The edges and corners of the substrate wear the screen printing plate;
b. Insufficient tension of the screen printing plate;
c. The screen frame is deformed.
