How Indian Enterprises Deal with Problems in UV Offset Printing

To make UV offset printing work better, the main issues that need to be addressed are the following:

1, design and plate making

The design draft for producing UV printing must determine the output format according to the work order, such as the film surface swept forward or reverse sweep, the number of output network lines, the angle of the network cable and so on. Some special printing requirements are high, such as 3D printing resolution is very high, the network line angle must match with the printing materials to avoid collision; transparent plastic sheet and aluminized paper often need to add white ink, should pay attention to the impact of printing material stretching , pre-correction film to achieve the best quality.

2, adhesion

Due to the poor permeability of substrates such as plastic sheets or gold-silver cardboard, the adsorption power of the ink is very weak. Even if UV ink printing is used, the ink adhesion is poor and the printing quality is not high. It can be solved by surface treatment of the material.

3, ink emulsification

UV ink ink balance tolerance is very narrow, easy to cause ink emulsification, dirty version, affect the printing quality. Solution: Reduce the printing speed, and control the printing speed at 5000-8000 prints/hour.

4, the degree of curing

In order to improve the color saturation of printed products, when printing on the surface of a plastic sheet or the like, the printing pressure is large, the ink layer is thick, and the dots are increased so that the ink is not easily cured. In order to ensure printing quality printing pressure can not be greatly adjusted. Solution: First, moderately reduce the printing speed, properly lengthen the UV lamp irradiation time, so that the ink is completely cured; followed by adjusting the distance between the UV lamp and the substrate, increase the UV light irradiation intensity, so that the ink curing. UV curing effective wavelength range is 200 - 400nm, the wavelength of some light sources in the printing room is also within this range, it will cause the ink surface layer to be slightly cured, so should pay attention to the effect of ambient light on UV inks.

5, color order arrangement

UV offset color arrangement problem is more complicated. Due to the limitation of inking principle, the ink layer on the substrate is relatively thin. When a relatively thick ink layer is needed, it is difficult for the printing product to achieve the desired reproduction effect. For example, in the case of four-color overprinting, the commonly used printing sequence is black, cyan, magenta, and yellow. Because black fills almost all the space, the ink strength of cyan, magenta, and yellow is lower, and the total amount of ink is insufficient. The color is not saturated.

The solution is to change the color sequence, first printing the ink with the smaller amount of color, and finally printing the black with the larger amount of ink, so that the ink can reach the highest level and the color can be more full.

6, print registration

UV offset printing uses UV light irradiation for ink curing. The main problem caused by curing is the thermal expansion of the substrate, resulting in inaccurate overprinting. This is inconsistent with the UV ink curing because the UV curing requires a longer irradiation time for the ink, and the printing sleeve criteria requires a shorter UV lamp irradiation time.

Solution: After the last color is printed, perform UV curing. Even if the substrate expands, lowering the temperature for a period of time can minimize the deformation of the substrate. Under special circumstances, the middle color group can also be exposed to UV light, but the shorter the irradiation time, the better.

Reprinted from: Packaging Expo