The problem with printing with letterpress parts is that the ink drying is too slow, premature aging and obvious odor, the reasons and solutions are as follows.
(1) The ink on the print is not dry and easy to wipe off
The oxidative polymerization drying of the letterpress printing ink is printed on the polyolefin film, and it takes 2 to 3 days or more to dry, and an appropriate amount of drier must be added. The amount of white dry oil is 5%~15%, and the red dry oil is 2%~5%. It can also be mixed, and the drying time can be shortened to 8~24h.
The printing ink is not dry. Except for the impurity contamination on the surface of the film or the humidity of the workshop is too large (relative humidity is above 95%), most of them are caused by insufficient amount of drier. However, the amount of white dry oil added should not be too much. If it exceeds 20% of the ink quality, sometimes the ink layer is dry, but it always has a sticky feeling, which may also cause the adhesion of the printed sheets after they are stacked. Therefore, the amount of driers added should be weighed and cannot be added randomly.
(2) The printing ink layer is easy to fall off after 1~2 months.
The letterpress zero-printing plastic ink is prone to aging and is easily peeled off by the enamel, which is a major drawback. However, under normal circumstances, it can be maintained for 6 months without aging. Premature aging is caused by excessive addition of drier or excessive UV light. Attention to control can avoid this drawback.
(3) The printed ink layer has a large odor
There is a red dry oil in the drier, which is mainly composed of cobalt naphthenate and manganese naphthenate. The naphthenic acid has an odor similar to that of strontium. When the red dry oil is added to the ink, it will have some odor. In addition, a red dry oil containing cobalt rosinate and manganese rosin as main components does not have such an odor, and the white dry oil has no odor, and the selection can be used to avoid the disadvantage.
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