(English)
In direct-to-film (DTF) printing, one of the most common challenges faced by manufacturers and print professionals is the issue of powder sticking to PET films. This issue not only affects the aesthetics of the final product but also compromises the quality and performance of prints. In this article, we will explore the main causes of powder sticking to PET films and provide effective solutions to address these issues, ensuring a smooth and high-quality printing process.
Air humidity plays a significant role in the powder sticking to the PET film, particularly during storage, printing, and powder shaking processes. Maintaining the right humidity levels is essential for preventing moisture absorption, which can cause excess powder to stick to the film, impacting the final result.
When PET film and hot-melt powder are stored in a humid environment, the absorption of moisture can cause excess powder to cling to the film during the powder shaking process. This results in uneven powder distribution and negatively affects the finished product.
Solution: Ensure that PET film and powder are stored in a cool, dry place. If necessary, use desiccants to absorb moisture. During printing and powder application, use air conditioning to stabilize the indoor temperature and humidity, creating optimal conditions for the printing process.
In a dry environment, low humidity can generate static electricity, which is particularly problematic during the white ink printing phase. Static electricity causes ink splashing, which in turn leads to powder sticking to the ink, leaving unwanted residues on the film and compromising the appearance of the final print.
Troubleshooting: To identify if static electricity is the cause, print two copies of a design—one with regular white ink and another in color only. Dust and dry both prints and compare the results. If the white ink print shows more powder adhesion, static electricity is likely the culprit.
Solution: Static electricity can be effectively managed with the use of humidifiers, anti-static rods, or by adjusting printing speed to reduce white ink output. These measures will minimize the impact of static and prevent powder sticking.
In some cases, excess powder may be applied during the shaking process, leading to damp powder that sticks to the film. This can happen when moisture from the ink or evaporation during the pre-heating and drying process causes the powder to adhere to the film, even after it has been shaken.
Solution: Replace any damp powder with dry powder and adjust the powdering process. Ensure that the amount of powder used is optimal—too much powder will increase the risk of moisture absorption and sticking.
The interaction between the PET film's coating density and the powder's fineness can also contribute to powder sticking. If the film has a low coating density and the powder is too fine, the powder may get stuck in the film's coating holes and fail to shake off completely.
Solution: Increase the shaking force of the powder shaker or manually tap the back of the film during powder shaking to dislodge excess powder. It is also crucial to choose the right PET film and powder that are compatible with each other. AGP offers carefully selected PET films and powders designed to work seamlessly with AGP DTF printers, providing optimal results across various application scenarios.
When printing at high speeds, the film may not have enough time to fully absorb the ink before the powder is applied, resulting in excessive moisture on the film. This moisture can cause the remaining powder to absorb water and stick to the film, leading to poor results.
Solution: To avoid this issue, allow the front and rear heating elements to bring the film to the correct temperature before proceeding with the dusting and shaking process. Printing at a moderate speed of 6-pass to 8-pass ensures stable ink absorption and prevents excess moisture from affecting powder adhesion.
Powder sticking to PET films is a common issue that can be caused by various factors such as air humidity, static electricity, powder fineness, and improper printing settings. By understanding these causes and implementing the right solutions—such as controlling humidity, managing static electricity, selecting compatible film and powder combinations, and optimizing printing speed and heating—you can significantly reduce the chances of powder sticking and improve the overall quality of your prints.
Call to Action: If you are experiencing issues with powder sticking to PET films in your DTF printing process, consider implementing the solutions outlined above. AGP offers high-quality PET films and powders designed to prevent such issues, ensuring a flawless print every time. For more information or to consult with our experts, don’t hesitate to reach out to AGP.
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