Gravure printing composite sheet

Unlike flexible printed composite sheets, gravure is printed on a PE film and then compounded with aluminum foil to make a composite hose. Therefore, the printing of the gravure on the composite sheet is actually the printing of the gravure on a single layer of PE.

1. Note the vertical and horizontal tensile strength of PE printing film

The commonly used PE printing film is a two-layer co-extrusion blown film, and its longitudinal tensile strength is related to the traction ratio when the film is blown. The traction ratio is the ratio of the film pulling speed to the billet extrusion speed, increasing the traction ratio, and increasing the longitudinal strength of the film. The transverse tensile strength of the film is related to the blow-up ratio when the film is blown. The blow-up ratio is the ratio of the diameter of the film tube to the diameter of the die, increasing the blow-up ratio, and increasing the transverse strength of the film. When the gravure is printed on the single-layer PE film, the distance between each color group of the gravure is 6-7m, and the heating temperature during drying is generally 50-60°C, which makes it particularly easy to stretch and deform the PE. Although there is a reliable automatic color registration tracker, the adjustment range of the automatic registration tracker cannot keep up with the deformation range of the single-layer PE film when heated and stretched. Therefore, the experience of the gravure printing process will always be found when printing PE. Not allowed. In fact, as long as you control the MD, CD, ie, the tensile strength in the longitudinal and transverse directions when blowing the film, be careful not to make it too large. At this time, pay attention to the ratio between the traction speed and the detection speed can not be too large, pay attention to the diameter and die of the film tube. The ratio of diameters cannot be too large.

2. Adjust the gravure printing plate according to MD and CD of PE printing film

Even if the MD and CD are controlled perfectly, the single-layer film will still be stretched during the printing process. At this time, the deformation parameters must be adjusted to the printing plate. When the gravure printing plate is printed in each color group, there is an incremental amount on the diameter. According to the specific MD and CD parameters, adjusting the vertical increment and the horizontal shrinkage is the premise to ensure the reliable operation of the automatic color registration on the printing machine. .

3. Pay attention to the adjustment of the tension during printing and the control of the drying unit temperature

In order not to make the longitudinal stretching too large to impede the accuracy of the overlay, attention must be paid to the adjustment of the tension. The tension setting value can not be too large. If the tension setting value is too large, the film can easily shrink and form irregular deformation. This will make it difficult to adjust the tracking range of trapping. The temperature of the drying unit should not be too high. If the temperature is too high, the film will become soft and easier to stretch. This must be avoided.

4. Note the use of the adjustment of the printing plate to mask the error of the plate

With the flexographic printing in the register printing should pay attention to the use of printing plate adjustments to cover up the same error, gravure also needs similar adjustments, do not underestimate these minor adjustments, which is of great benefit to the user's visual impression of the print.

Reprinted from: China Print Online