Bottle printing ink

Some Factors Affecting the Adhesion of the Ink in the Screen Printing Process of Bottles

A bottle of material:

Print material if it is not pure

If the printing material is not pure, it will have a considerable impact on the adhesion. In the current market, the impure printing material is mainly expressed in the synthetic material and material. Due to the differences in the processes of different companies during the injection molding process, the surface of the plastic material shows different conditions. Many materials have grease on the surface, which affects its adhesion. The color of the bottle's material also has an effect on the UV light reception, which also affects its adhesion.

Two bottles of prepress processing

In order to obtain good adhesion of the ink to the substrate, the bottle must be polarized to achieve a surface tension of not less than 3.8 x 10-2 N/m. (In general, the ink is good for the substrate. The most basic condition for adhesion is that the surface tension of the substrate is at least 50 dyn/cm.)

The method of polarizing the bottle is mainly flame treatment. The principle of flame treatment is to decontaminate the plastic surface through high temperature and melt the surface of the film layer, thereby increasing the surface energy of the plastic bottle and improving its surface adhesion to the ink. All in all, before the printing, it is necessary to ensure that the surface of the substrate is clean and the polarisation is effectively treated. The surface treatment of the bottle is incomplete and the adhesion must be influenced.

Flame treatment

The flame processor is composed of conveyor belts, tapered inserts, flame nozzles and gas tanks. When used, the plastic bottle is placed on the tapered insert and the conveyor belt moves forward uniformly. Before reaching the flame nozzle, the conical insert starts to rotate, and at the same time, the bottle is rotated, and the blue flame ablates the surface of the plastic bottle. Improve the surface energy of plastic bottles and increase the binding force with ink. The strength of the flame, the running speed of the conveyor belt, and the smoothness of the rotation of the bottle all directly affect the treatment effect, among which the smoothness of the rotation of the bottle is the most critical. The degree of 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. The commonly used method is to attach a nylon sleeve to the tapered insert. The inner diameter of the sleeve is also conical, and the outer diameter is equal to the size of the bottle mouth. The jacketed bottle cannot drop on its own and must be removed manually. The flame-treated plastic bottles should be immediately printed, otherwise the surface energy of the plastic bottles will be reduced, and the secondary dust will be easy to affect the adhesion of the ink.

Flame treatment effect detection

The easiest method is to use a surface tension test pen for testing. The 3.8×10-2N/m specification surface tension test pen is used. If the liquid marks in the test stroke spread evenly and do not shrink, it indicates that the treatment effect is better; if the liquid mark shrinks, or the liquid mark partially shrinks, collapses. If the part does not shrink, it means that the processing is not sufficient. Or you can use "splash treatment" to detect, if handled well, on the surface of the plastic bottle, will form a dense layer of "water film", which is often referred to as silk screen counterparts "Sheung Shui." The effect of time-dependent polarization treatment on the surface of the bottle has a certain timeliness. The longer the time, the worse the effect, and the poorer the binding force with the ink, ensuring the adhesion of the ink, and printing should be performed immediately after processing. The survey found that due to the limitations of the customer's production process, most printing plants do not have the same polar processing and printing department. This will cause printing lag, which will affect the adhesion of the ink and the bottle.