Find the reasons for poor ink adhesion from these four aspects!
Time:2025-02-25
Views:26
Printing ink
1.Improper ink selection
Different types of ink are suitable for different film materials, and the ink used for different products also varies. If the adaptability between ink and film is poor, and the affinity between ink and film is poor, it will lead to poor ink adhesion. Therefore, before printing, it is necessary to select the corresponding ink type based on the characteristics of the film material and the product requirements used, and it cannot be consistent.
2.Unreasonable ink formula
The ink formula directly affects its adhesion performance, especially the selection of ink resin, which directly affects the performance of the ink. If the combination of resin, pigment, solvent and other components in ink is not reasonable, such as a decrease in resin binder, it may lead to a decrease in ink film-forming performance, a decrease in ink film cohesion, and thus a decrease in ink adhesion.
3.Improper storage of ink
Improper storage of ink can also lead to a decrease in ink performance. Generally, ink stored for a long time has a relatively low resin content. If ink stored for a long time or expired ink is used for printing, it will cause a decrease in ink performance, thereby affecting the adhesion of ink on film materials.
4. Insufficient proportion of ink resin
Thin film materials
1.Surface tension of thin film materials
Commonly used film materials such as polyethylene, polypropylene, nylon, polyester, etc. have a very smooth surface and no affinity for ink. Ink is not easily attached to them and requires special treatment to change their surface condition and chemical structure, increase surface roughness and intermolecular polarity, in order to make the ink bond firmly. The adhesion of ink on the surface of film materials is closely related to the surface tension of the printed film materials. If the surface tension of the film material is lower than that of the ink, it is difficult for the ink to form a good adhesion on the surface of the film material. Therefore, appropriate treatment (such as corona treatment) should be applied to the film material before printing to increase its surface tension.
2. Surface cleanliness of thin film
The pollutants on the surface of the film can affect the adhesion effect of the ink, such as oil stains, dust and other impurities, which can lead to a decrease in the adhesion between the ink and the film material.
3. Additive precipitation
Most printing films contain various additives, such as antistatic agent, smoothing agent, opening agent, plasticizer, anti-aging agent, etc. These additives will form a barrier layer on the surface of the film, which will damage the adhesion of the ink to the base film and greatly reduce the printing firmness.
4. Storage Environment
The storage conditions for the film are not suitable, such as excessive humidity, and some film materials (such as nylon, polyester, etc.) are prone to moisture absorption during storage. After absorbing moisture, the surface tension of the film material will decrease, which can easily lead to a decrease in ink adhesion. In addition, storing the film beyond its expiration date can also lead to a decrease in the surface properties of the film, resulting in a decrease in the adhesion of the ink to the substrate.
Printing process
1. Ink moisture absorption emulsification
Ink emulsification refers to the dispersion and coagulation of ink in environments with high water or humidity. Ink moisture absorption and emulsification can easily cause a decrease in the adhesion and cohesion of the resin, resulting in a decrease in ink adhesion.
2.Ink layer too thick
During the printing process, if the ink layer is too thick, it will cause the ink to form an uneven coating on the surface of the film material, resulting in false drying and affecting the ink adhesion.
3. Ink drying is not thorough
The printing speed and the drying ability of the equipment have a significant impact on the ink‘s thorough drying performance. Excessive printing speed can lead to incomplete ink drying, and the ink may not form a good adhesion on the surface of the film material in time, which can easily cause detachment.
4. Insufficient proportion of ink resin
During the printing process, excessive dilution of ink can lead to a decrease in resin content, resulting in a decrease in ink adhesion and thus affecting the adhesion of the ink.
Environmental temperature and humidity
1.Environmental temperature
The temperature determines the activity of intermolecular motion in thin film materials. Under higher temperature conditions, the viscosity of the ink decreases, the surface activity of the film increases, the transfer and adhesion properties of the material are improved, and the leveling and wetting properties of the ink solvent increase. Therefore, the ink can achieve better adhesion.
2.Environmental humidity
Humidity also has a certain impact on the adhesion performance of ink. Excessive humidity can form a water droplet barrier layer on the surface of the film, allowing water vapor to enter the ink and emulsify the ink resin. This unsuitable high humidity environment may lead to a decrease in ink adhesion.
In summary, the reasons for poor ink adhesion involve multiple factors such as ink performance, film material, printing process, and environment. In the actual printing process, the reasons can be analyzed based on specific situations and corresponding solutions can be taken to improve the adhesion of ink on the surface of the film. For example, ink that matches the film should be selected, and high-quality ink should be chosen as much as possible to avoid poor ink adhesion from the source; Select solvents that match the ink and printing conditions, and maintain good solubility, dryness, and wetting properties of the solvents; Pre treat the surface of the film to maintain its adhesion properties, and check the surface tension of the film before use; Strictly implement the storage management measures for ink and film, control the temperature and humidity of the environment, ensure the cleanliness of the storage environment, and follow the principle of "first in, first out" to avoid expired use.
In summary, the reasons for poor ink adhesion involve multiple factors such as ink performance, film material, printing process, and environment. In the actual printing process, the reasons can be analyzed based on specific situations and corresponding solutions can be taken to improve the adhesion of ink on the surface of the film. For example, ink that matches the film should be selected, and high-quality ink should be chosen as much as possible to avoid poor ink adhesion from the source; Select solvents that match the ink and printing conditions, and maintain good solubility, dryness, and wetting properties of the solvents; Pre treat the surface of the film to maintain its adhesion properties, and check the surface tension of the film before use; Strictly implement the storage management measures for ink and film, control the temperature and humidity of the environment, ensure the cleanliness of the storage environment, and follow the principle of "first in, first out" to avoid expired use.
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