Sixth, after the printing of steel drum graphics surface cracks and cracks
After the steel drum was printed, the cracking phenomenon of the image and text was mainly caused by the effect of the solvent and the large temperature change. In addition, when using the scraper to scribble graphics on the steel drum, if the scraper pressure is insufficient, the ink sticky and the flow is not smooth, the printing ink layer will be false, and the white dot phenomenon will occur; if the scraper pressure is too large, When the fluidity is high and the viscosity is low, the ink will permeate between the edge of the plate and the steel drum, and ink inward tends to occur. Under the pressure of the squeegee, when the ink is transferred to the surface of the steel drum, the ink is pulled between the steel drum and the stencil plate at the moment of separation, and is transferred to the surface of the steel drum and adhered to the screen plate. In part, the following situations will occur:
1. The ink fills the gap in the screen plate.
2. The ink is under pressure from the squeegee and is in a contracted state.
3, off the plate, the ink was dragged between the wire mesh and steel drums.
After the ink is broken, the viscoelasticity is restored to its original shape. This splitting phenomenon depends on the viscoelasticity, the off-plate speed, the interfacial tension between the ink and the screen plate, and the absorbability of the ink on the steel drum. The phenomenon of splitting is an important factor in the formation of ink ink layers.
In order to prevent the occurrence of cracking and splitting of the ink layer, it is necessary to consider the properties of the ink and the solvent resistance of the drum surface after coating, and pay attention to the temperature and humidity at the printing site to effectively prevent the ink. Cracking and splitting of the membrane occur.
Seven, silk screen leaking ink
When printing graphics on the surface of steel drums, dust and ink in the drum should not be mixed with dust. If these dusts are not processed, the printing plate will be damaged due to the action of the blade pressure, and the pinholes will be generated when the plate is underexposed. These factors will cause ink leakage in the plate. At this time, tapes and the like can be used for emergency handling from the back of the screen plate. If this operation is not very fast, the ink on the screen will dry, and the whole surface must be wiped with solvent. Wiping plates is also a factor that causes stripping, so it is best avoided. In addition, the ink leakage of the screen printing plate often occurs at the portion where the ink stays, so it is preferable to reinforce this portion at the time of plate making.
In the process of printing graphics by hand on steel drums, it is first necessary to check whether the ink is pure and cannot be mixed with iron filings, iron stabs and dust. Also check that the surface of the drum is smooth and avoid dust and iron stabs. Because the sharp corners easily pierce the screen plate, ink leakage occurs. Therefore, the screen plate must be inspected and reinforced before printing. In addition, we must carefully carry out graphic errors and pinhole correction of the film to reinforce the surrounding of the plate. The so-called reinforcement is to glue some plastic tape on the back of the screen plate. Try to avoid printing because of the screen version and ink, scraper and other failures and stop working.
VIII. Printing and Printing of Steel Barrels
(a), AIDS
Moisture ink refers to the appearance of spot-like marks on the surface of the drum surface in the graphic and neutral sections. This phenomenon damages the printing effect. The reasons for this phenomenon are:
1, the printing speed and the ink drying speed are too slow.
2, ink ink layer is too thin.
3, the thixotropy of the ink is too large.
4, when printing, the impact of static electricity on it.
5. Polarity of the pigment particles in the ink, particles agglomerate, and color dot blots appear.
How can we improve and eliminate the occurrence of AIDS? In general, starting from the following aspects:
1. Improve the fluidity of the ink;
2, the use of fast-drying solvents;
3, as much as possible with high viscosity ink printing;
4. It is recommended to use ink made from pigments with small oil absorption.
5. Minimize the effects of static electricity.
(b) Flying ink
Flying ink is the drawing of ink. The reasons for this phenomenon are:
1, ink uneven grinding;
2. The squeegee is slow from printing when printing;
3, there are few gaps in the printing of graphics;
4, generate static electricity, resulting in ink drawing;
5, scraper angle is too small.
The solution is:
1. To replace the ink with good quality, when mixing ink, be sure to mix evenly;
2. Pay attention to the speed of off-printing when printing;
3, there should be an appropriate gap when making plates;
4, always check and repair scraper edge.
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