UV INK PRINTING PROBLEMS
In the realm of industrial screen printing ink, the various series of UV ink exhibit a wide range of applications, leading to diverse requirements and consequently, numerous challenges. This discussion focuses on common UV printing problems encountered with UV screen printing ink and their treatment methods.
1. **Long-Term Layering of Ink**: This phenomenon, particularly evident with gloss oil, is normal. It is crucial to thoroughly stir the ink before printing with the machine to avoid surface effects on the printed material caused by prolonged ink layering, which can lead to defoaming and flow issues.
2. **Paste Plate Phenomenon**: Products such as embossing polish and those prone to refraction may experience this issue. The main causes include high viscosity, inadequate screen tension, low screen distance, soft scrapers, uneven or overly thick ink, and insufficient pressure. Proper adjustments in the printing process and adding thinner to the ink can help rectify this.
3. **Incomplete Printing Patterns**: This issue may arise from insufficient pressure during printing, inadequate scraper hardness, or low screen mesh tension. The choice of ink also plays a role; inappropriate varieties or poor wettability on the substrate can lead to incomplete patterns. Sometimes, issues may stem from UV light exposure during the printing process.
4. **Bubbles and Concave Spots**: Possible causes include insufficient stirring of the ink, high viscosity, dust on the substrate, contamination during the printing process, or excessive absorbency of the substrate leading to UV ink penetration and small pitting spots.
5. **Poor Adhesion of UV Ink Printing**: Adhesion problems may arise from inappropriate selection of UV ink based on the substrate's polarity, flexibility, and cleanliness. Additionally, subpar UV curing equipment can lead to incomplete curing, diminishing adhesion. Variations in the printing process, such as incorrect ink layer thickness or improper use of additives, can also result in weakened adhesion.
6. **Sticky Printed Matter**: This issue often occurs during stacking and post-processing, especially in warmer conditions or with thin double copper paper. It typically happens when UV ink is not fully cured. To address this, consider the ink varieties, type of substrate, thickness of the ink layer, and ensure effective curing through proper ventilation.
7. **Problems with UV Special Effect Ink**:
- *UV Wrinkle Ink*: Control over wrinkle size is essential and closely tied to factors like curing time and printing thickness. The choice of substrate is crucial for adhesion.
- *UV Scrub Ink*: Select the right varieties for matte film paper and be mindful of mesh distance.
- *UV Refraction Ink*: Precision in mesh count and scraper strength is vital to avoid pasting issues.
- *UV Embossing Varnish*: Printing at low mesh counts can lead to virtual edges or bubbles; thus, scraper angle and speed should be adjusted accordingly.
- *UV Foaming Ink*: High requirements for the printing process necessitate detailed documentation during testing to ensure quality.
- *UV Snow Ink*: Use two sets of light curing machines, ensuring energy levels are adjusted to achieve the desired snowflake pattern.
- *UV Powder Varnish*: Incorporating color powders can impact curing, necessitating careful selection of ink varieties and adjustments to UV energy levels.
8. **UV Ink Preservation and Printing Environment**: Store UV inks in a cool, ventilated area below 30℃, and cover ink buckets immediately after use to prevent contamination. Ensure a cool and well-ventilated printing environment to mitigate sunlight exposure and UV light from curing equipment, which can reduce adhesion and protect against skin and eye irritation from UV ink materials.
