1.1 Ink adhesion mechanism Wetting: Adhesion fastness is the result of the interaction between the molecules of the printing substrate film and the ink binder.
Compatibility: The polarity of the ink connecting material is similar to that of the substrate, indicating good compatibility. (Be sure to choose ink that matches the printed material).
1.2 Reasons and countermeasures for weak adhesion and substrate factors.
a. The corona treatment degree on the surface of the substrate is not sufficient, and it has not reached the required tension, or the surface of the treated substrate has been stored in a poor environment for too long, resulting in surface tension attenuation and failure.
Generally, the surface tension of PP and PE is required to be ≥ 38mN/m, PET≧50mN/m，NY≧52mN/m。 Before use, the surface tension of each batch of film should be checked.
b. Most substrates are processed with added lubricants, anti-static agents, moisture-proof agents, etc. These additives slowly penetrate from the film to the surface over time, forming a weak interfacial layer on the film surface that affects ink adhesion. Therefore, the film should be used within its validity period and the surface tension should be tested before use. Can be tested with a Dain pen. The factor of substrate moisture absorption. For example, materials such as PA, PVA, PT, etc. are prone to moisture absorption and reduce adhesion. These substrates should be stored under good conditions (controlled temperature and humidity) and thoroughly preheated before use. Wrong type of ink used, mixing different types of ink.
There are many types of ink for gravure printing, including surface printing ink and inner printing ink. Different materials correspond to different inks, and various specialized inks must be used correspondingly, otherwise the adhesion strength is not enough. Before production, the operation process instructions should be checked. Ink whitening. Ink deterioration and whitening greatly reduce adhesion. Insufficient ink drying. Insufficien
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