What are the factors that affect the adhesion of glass screen printing inks?
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First, the bottle material
If the material of the printing material is not pure, it has a considerable influence on the adhesion. In the current market, the printing material is not pure mainly in the synthetic material and the nozzle material. Due to the difference in the process of different companies during injection molding, the surface of the plastic material presents different conditions. Many materials have grease on the surface, which will affect its adhesion. The color of the bottle material also has an effect on UV reception, which also affects its adhesion.
Second, the pre-press treatment of the bottle
In order to obtain good adhesion of the ink to the substrate, the bottle must be polarized so that the surface tension of the bottle is such that the surface tension is not less than 3.8×10-2 N/m (generally, the ink is well attached to the substrate) The most basic condition for the force is that the surface tension of the substrate is at least 50 dyn/cm or more.
The method of polarizing the bottle is mainly flame treatment. The principle of flame treatment is to decontaminate the plastic surface by high temperature and melt the surface of the film layer, thereby improving the surface energy of the plastic bottle and improving the adhesion of the surface to the ink. All in all, the surface of the substrate must be cleaned and effectively polarized before printing. The surface treatment of the bottle is not thorough and the adhesion will inevitably have an effect.
Third, the flame treatment
The flame processor is composed of a conveyor belt, a tapered plunger, a flame nozzle and a gas tank. In use, the plastic bottle is placed on the tapered plunger, and the conveyor belt moves forward at a constant speed. Before the flame nozzle, the tapered plunger starts to rotate, and also drives the bottle to rotate, and the blue flame ablates the surface of the plastic bottle, thereby Improve the surface energy of plastic bottles and increase the adhesion to ink. The strength of the flame, the running speed of the conveyor belt, and the smoothness of the bottle rotation directly affect the treatment effect, and the smoothness of the bottle rotation is the most critical. The smoothness is proportional to the size of the bottle. The shorter the bottle, the smaller the radius and the better the effect after treatment. For larger bottles, we must take measures to increase its smoothness. A common method is to attach a nylon sleeve to the tapered post. The inner diameter of the sleeve is also tapered, and the outer diameter is the same as the size of the bottle. The set of bottles cannot be dropped by themselves and must be removed manually. The flame-treated plastic bottle should be printed immediately, otherwise the surface of the plastic bottle can be reduced, and it is easy to be dusted twice, which affects the adhesion of the ink.