Home > News > Content
UV Inks Do More With Less In The Process Of Label Flexo Printing, UV Inks Do More With Less!
- May 28, 2018 -

UV ink has many advantages such as fast curing speed, high printing color density and good stability, as long as it does not contact with ultraviolet rays, it will not dry in the ink fountain, has small odor and is basically free of VOC. It has been widely used in label flexo printing. . However, in actual printing, it will inevitably encounter some problems, such as incomplete curing, poor adhesion, line-shaped color spots, and low light fastness. The following will analyze the causes of these printing problems and summarize the corresponding solutions. Method.

Remember to take a good book, do record Austria!

01 ink curing is not complete

Problem Description

There is ink on the paper guide roller between the printing units and it will be transferred to the printing material; the back of the printing product will be dirty after winding.

Cause analysis and solution

Solve the problem of incomplete UV ink curing from the curing device, the printing operation, the ink itself to find the reasons, and then symptomatic solution.

First of all, check whether there are dirt on the surfaces of UV lamps and reflectors to prevent the UV light from irradiating the printed products. If so, clean them, and develop the habit of using regular alcohol to clean UV lamps, lamp shades, and reflectors. At the same time, check the usage time of the UV lamp. If it has exceeded the service life, it must be replaced to ensure that the UV lamp has sufficient power; or set several UV lamps to increase the UV radiation energy.

Excessive printing speed will cause insufficient UV radiation energy received by the UV ink, and the curing time is too short, resulting in incomplete UV ink curing, which can be solved by reducing the printing speed. Too thick ink layer will cause only the UV ink surface layer curing and internal curing is not complete, then need to change the anilox roller, reduce the amount of ink properly, reduce the ink layer thickness.

The above are all external causes of incomplete UV ink curing, and the internal cause is that UV light absorption spectrum of UV ink itself is relatively narrow compared with the emission spectrum of UV light. At this time, a suitable photosensitizer can be added to the ink. The addition ratio is 1% to 3%, and the curing efficiency is improved by expanding the absorption spectral range of the ink, thereby improving the curing effect.

02 Ink adhesion is poor

Problem Description

When using the 3M-600 adhesive tape for the ink adhesion test, the ink is peeled off from the surface of the printing material, or the ink after the printing is peeled off from the ink layer.

Cause analysis and solution

Improper selection of substrates or low surface tension is the most common cause of poor adhesion of inks. If printing materials and printing inks do not match, they need to be replaced. For plastic film materials, the surface tension can be increased by corona treatment, or the coating can be increased. Layers to improve its adhesion, in general to ensure that the surface tension of 38 dyne or more.

In some cases, poor ink adhesion is also associated with the ink formulation. If the test compares different batches of ink for this problem, a layer of primer may be preprinted prior to printing the ink.

When using the first hot after-printing process, if the adhesion of the ink on the surface of the hot stamping foil is poor and it is easy to fall off, the varnish may be applied for protection.

The poor adhesion between the ink layers is often caused by excessive curing of the previous color ink, and the curing power of the previous color set UV lamp can be appropriately reduced.

Incomplete ink curing is also one of the causes of the poor adhesion of the ink layer. To find the cause, take appropriate measures.

Copyright © Dongguan Xianglee Printing Co.,Ltd. All Rights Reserved.