The technique of machine printing to obtain stereoscopic thick effect

Stereo thick effect is usually obtained by handprinting in printing. Judging the pros and cons of stereoscopic thick printing, ink thickness is critical. At present, many printing plants print the effect of stereoscopic thick printing, or they are hand-printed. Generally, they must print 15 to 20 times to reach the required thickness. Although some factories have fully automatic printing machines, they do not know how to make stereoscopic thick effects.

How to use a full-automatic printing machine to easily obtain the effect of stereo thick printing and improve the production efficiency is a concern for many printing manufacturers.

Machine can be printed in one circle to get stereo thick effect

With a fully automatic printing machine, it is possible to print stereoscopic thick effects with one revolution, but it is necessary to master some key method techniques. Mastering the operation method and printing technology of the printing machine is a precondition, but it is also necessary to understand a special process that is specially used for stereo thick printing.

1, screen

Three-dimensional thick net yarns must be used for low mesh purposes, such as 32 mesh/cm, 34 mesh/cm, and 40 mesh/cm. In addition to the low mesh size, it is also the diameter of the filaments. Such mesh yarns are easy to pass through the mesh and have a smooth surface. When stretching the net, it is necessary to pull the screen to a higher tension so that it is easy to lift the net. (Recommended 30-40 Newton)

According to the thickness of the ink, 3D screen printing screens and 4 screen printing screens can be used to produce the stereoscopic thick printing effect. The first is usually a thin screen printing transparent bottoming, available 32 mesh / cm screen, film thickness of 100 microns, after drying and then print 32 mesh / cm screen, 300-400 microns film thickness, if After reaching the thickness, a screen cover of 48 mesh/cm and 300-400 micron thickness can be used later to ensure a smooth surface. If the thickness is not enough, a screen of 32 mesh/cm and 300-400 micron thickness can be added in the middle. , so that you can print enough solid stereo effect in a circle.

Key point: Use thick film film to reduce sun screen, high tension screen

2, oil ink

Must use a certain consistency of ink, such as the consistency of the ink is not enough, it is impossible to achieve a thick printing effect. In thermosetting inks, it is recommended to use transparent inks that are specifically designed for stereo thick printing. For example, the HD-0138 of Rutland, USA, is a transparent ink that is used for printing stereoscopic thick printing effects. This ink can be used directly, and it can also be used to add color tones. (The American ICC 141LF is usually not thick enough, and you can use it by adding appropriate thickening powder and stirring it.)

Printing stereoscopic thick printing effects, usually divided into several situations: First, the bottom of the transparent ink is printed to a certain thickness, cover a color surface. The second is to add color to the transparent ink, which has the same effect from bottom to top. The third is the use of transparent ink from the bottom to the surface, printing a three-dimensional transparent thick version of the effect. Fourth, the bottom layer is printed with a thin layer of color with a thick transparent effect. However, no matter what kind of effect is printed, the change is only in color, and the printing method is the same.
Key point: ink consistency is better

3, mesh size, ink strength and squeegee speed

Network size When printing stereoscopic thick version, the net distance is very important, which is totally different from the ordinary effect. The net distance required for each screen printing is higher than that of the previous screen version. The screen height is determined according to the ink height after the previous screen printing. That is, the screen pitch must be adjusted according to the height of the ink surface, instead of being adjusted according to the height of the cloth surface. Otherwise, the purpose of ink thickening cannot be achieved. The size of this mesh should be matched with the tension of the screen to achieve the best results.

Back to the ink In the ordinary printing, the ink strength can not be too large, too much force will make the pattern blurred. However, when printing stereoscopic thick printing, it requires a large back-inking force and a smaller angle of the ink-returning blade. In this way, the ink can fully fill the mesh when ink is returned, and complete ink transfer can be achieved. Ink is not good, ink thickness will not be printed and there will be uneven surface.

At the time of printing thick printing, the speed of ink scraping must be slow, because very thick ink must pass through a very thick screen, and it must have a process of ink and cloth bonding, and the ink will not be normal at too fast speed. With peeling, the ink cannot be completely transferred.

After adjusting the net distance, setting proper ink repellency, and slow squeegee speed, only one knife can be used to achieve a good transfer effect, and the ink thickness and surface smoothness can be guaranteed.

Key points: Network distance increases one by one, ink repulsive force is greater, and squeegee printing speed is slower

4, drying temperature

Post-press drying is the key step to ensure stereoscopic thick plate effect.

The curing temperature of the thermosetting ink can be completely cured in a short time at 160°C. It is for the thinner ordinary effect, and the thick plate effect at 160°C requires an extended time to fully cure to meet the pulling force. And washing fastness requirements. (Please note that the 160°C here is the temperature in the drying tunnel. It is the temperature measured when the thermometer passes through the tunnel in the oven along with the cut pieces, not the temperature shown in the temperature control table outside the oven. Because the outside of the oven temperature display and the temperature of the furnace sometimes varies greatly, especially some home-made oven.) Sometimes the need for a bright surface of the ink, the oven temperature can be adjusted to 170 °C -180 °C can be bright Oil surface effect.

Gas ovens should be the best choice for temperature control and drying effects. Because the gas oven has a very large air flow and baking power. You want to completely dry and solidify the surface of the thermosetting ink. Air flow and drying power are all required. Especially when we print thick or other special effects inks and special processes, we need to dry those aqueous inks containing a lot of moisture. At the time, the gas oven can recover the loss of heat faster than the electric oven, maintaining the constant temperature inside the oven.

Key point: Choose enough drying temperature, if necessary, buy gas oven
Author/Wang Hui Information Source: Screen Printing Process