Solution to color change of water-based ink in flexographic printing

Date: Sep 21 2024 From: Star Color

The reasons for color changes in water-based ink during flexographic printing are multifaceted, and can be attributed to three main categories: raw material factors, printing process factors, and external environmental factors. The following is a specific analysis:

Raw material factors

Quality issues with the ink itself:
Uneven dispersion of pigments: The dispersion state of pigments in ink directly affects the color effect of printed materials. If the pigment is unevenly dispersed, it can cause spots or stripes in the printed color.
Poor dryness of ink: The drying speed of water-based ink is relatively slow. If the dryness of ink is poor, it will cause the ink to not dry sufficiently on the substrate, thereby affecting the stability of color.
Ink shelf life: During storage, the composition of ink may change, leading to unstable color. Using ink that has exceeded its shelf life can also easily cause color changes.

Substrate characteristics:
Ink absorption: The ink absorption of the substrate can affect the penetration and adhesion of ink on the substrate. A substrate with excessive ink absorption may cause ink to penetrate too quickly, resulting in a lighter color; However, substrates with weak ink absorption may result in weak ink adhesion, affecting color stability.
Surface characteristics: The smoothness and roughness of the substrate surface can also affect the adhesion and color effect of ink. For example, a substrate with a rough surface may result in uneven ink distribution, leading to color deviation.

Printing process factors

Printing pressure and speed:
Insufficient printing pressure may cause ink to not be fully transferred to the substrate, resulting in lighter colors; Excessive printing pressure may lead to excessive ink penetration, which also affects color stability.
Printing speed that is too fast or too slow may also affect the transfer and drying process of ink, resulting in unstable color.

Layout cleaning and ventilation:
The printing plate needs to be thoroughly cleaned before use to avoid contamination of new ink by old ink residue, which can cause color changes.
Lack of oxygen in the layout can affect the oxidation reaction between water-based ink and oxygen in the air, thereby affecting the stability of ink color. Maintaining the ventilation of the layout is also important.

Humidity control:
Water based ink printing requires a certain humidity environment. Insufficient humidity can cause ink to dry too quickly, affecting the stability of color; Excessive humidity may lead to problems such as excessive ink penetration or the formation of watermarks.

Flexographic Printing Workshop

External environmental factors

Lighting conditions:
Long term exposure to strong sunlight may cause color fading in printed materials. This is because the pigments in the ink undergo photochemical reactions under the action of ultraviolet light, resulting in a lighter or changed color.

air pollution:
Chemicals in the air may react with ink, causing color distortion or fading. For example, certain acidic or alkaline gases may undergo neutralization reactions with the components in the ink, affecting the stability of the color.

Long term storage:
During long-term storage, the composition of water-based ink may change, such as pigment precipitation and water evaporation, leading to unstable color.
In summary, the reasons for color changes during water-based ink printing are multifaceted and require comprehensive consideration of multiple factors such as raw material quality, printing process, and external environment.

To avoid the problem of color change, the following measures can be taken:
Choose high-quality water-based inks and substrates to ensure stable and reliable ink dispersibility, dryness, and other properties.

Strengthen the control and management of printing processes to ensure that printing pressure, speed, humidity, and other parameters are within a reasonable range.

Do a good job in post-processing and storage of printed materials to avoid prolonged exposure to adverse environments that may cause color fading or distortion.

The water-based ink produced by Zhongzhixing Color is an environmentally friendly product that does not contain harmful substances such as VOCs and has no pollution to the environment. Meanwhile, its fast drying speed can significantly improve printing speed and production efficiency. This feature not only meets current environmental requirements, but also satisfies the printing industry's demand for efficient production.