1. Poor Adhesion
Cause: Insufficient surface treatment of PE or PP films leads to low surface tension, resulting in poor ink adhesion. Additionally, over-dilution of ink, damaged binders, or inappropriate diluents can also contribute to this issue.
Solution:
1.Surface Treatment: Ensure the film is treated properly with corona treatment to increase surface tension.
2.Ink Dilution: Use the correct diluent and avoid over-diluting the ink. Consult the ink manufacturer if necessary to select the appropriate ink type for better adhesion.
2. Ink Buildup
Cause: Impurities in the ink, excessive viscosity, or fast printing speeds can lead to ink buildup during the printing process.
Solution:
1.Filtering Ink: Filter the ink to remove impurities or replace it with new ink.
2.Adjusting Viscosity: Add a suitable diluent to adjust viscosity to the required level.
3.Drying Speed: If ink dries too quickly, incorporate a slow-drying diluent to manage the drying rate.
3. Color Difference
Cause: Variations in ink viscosity, inconsistent printing pressure, or clogged/worn anilox rollers can cause color discrepancies in prints.
Solution:
1.Ink Preparation: Stir and dilute ink simultaneously to ensure uniform consistency. Consider using a mechanical circulation pump for thorough mixing.
2.Regular Dilution: Add diluent every 30 minutes during printing to maintain optimal ink concentration. After multiple dilutions, refresh with original ink to stabilize viscosity.
4. Color Mixing
Cause: Contamination of subsequent ink colors from previous inks can occur due to slow drying times, high viscosity, substrate plasticizers, or unsuitable pigments/dyes.
Solution:
1.Drying Control: Ensure that previous inks are fully dry before applying subsequent colors. Adjust heating system temperatures accordingly.
2.Viscosity Management: Reduce ink viscosity as needed to minimize mixing risks.
3.Substrate Selection: Understand the types of plasticizers used in substrate films; change the film type if inappropriate plasticizers are present.
4.Ink Composition: Avoid inks based on dyes as raw materials, as they are more prone to migration issues.
5. Rewinding Adhesion of Printed Materials
Cause: Slow ink drying speed, excessive residual solvent, high rewinding tension, or elevated temperature and humidity during rewinding can lead to adhesion issues.
Solution:
1.Drying Adjustments: Use a fast-drying diluent or increase the drying temperature to reduce residual solvent.
2.Tension Adjustment: Lower the rewinding tension to prevent excess pressure during rewinding.
3.Temperature Control: Ensure that the drying temperature is appropriate and extend cooling time to allow proper heat dissipation.
6. Fuzzy Edges and Irregular Ink Spreading
Cause: Improper pressure between the ink roller and printing plate, dried ink on rollers, excessive ink viscosity, or static electricity can cause fuzzy edges or irregular splashes.
Solution:
1.Pressure Adjustment: Modify the pressure settings between the ink roller and the plate to optimal levels.
2.Ink Management: Use slow-drying thinners to manage ink consistency, and ensure ink trays are covered to limit evaporation.
3.Static Control: Install an electrostatic elimination device or add antistatic agents to the ink to reduce static-related issues.
7. Doctor Blade Lines and Ink Streaks
Cause: Foreign objects on printing plates, excessive pressure or wear on the doctor blade, or impurities in the ink can result in streaks or lines.
Solution:
1.Inspection and Cleaning: Regularly inspect and clean printing plates; replace if necessary.
2.Doctor Blade Adjustment: Adjust the pressure on the doctor blade or replace it if worn.
3.Filtering Ink: Filter the ink to remove any impurities that may contribute to streaking.
8. Ink Smearing
Cause: Poor ink drying, residual solvents, high rewinding tension, or using double-sided surface-treated films can lead to ink smearing.
Solution:
1.Faster-Drying Inks: Use faster-drying inks or thinners to improve drying times.
2.Temperature and Circulation: Check and adjust dryer temperatures and air circulation between color applications.
3.Tension Management: Reduce rewinding tension and consider using single-sided treated films if applicable.
4.Anti-SMearing Agents: Apply anti-smearing powder if smearing persists.
9. Ghosting
Cause: Appearance of unwanted dots or patterns can result from insufficient ink viscosity, worn anilox rollers, or improper roller ratios.
Solution:
1.Viscosity Control: Adjust ink viscosity to ensure adequate thickness for transfer.
2.Roller Maintenance: Replace worn anilox rollers and ensure the screen angle is appropriate.
3.Anilox Roller Ratio: Use an anilox roller with a suitable line count that matches the printing plate screen line count.
10. Pinholes and Intermittent Spots
Cause: An uneven film surface, dirt on cylinders, or excessively fast ink drying can create pinholes or spots in the print.
Solution:
1.Film Quality: Replace the film if it has inconsistencies or defects.
2.Ink Thickness Adjustment: Increase ink film thickness or printing pressure.
3.Cleaning Protocols: Regularly clean impression cylinders and check for wear on anilox rollers.
4.Viscosity Management: Use slow-drying diluents to enhance ink flow and reduce drying speed.
11. Ink Color is Too Light
Cause: Low ink viscosity, dried ink on rollers, incompatible substances mixed in, poor film surface adhesion, unsuitable pressure settings, or a high line count on anilox rollers may lead to light ink color.
Solution:
1.Viscosity Adjustment: Add original ink or binder to enhance color strength.
2.Managing Dried Ink: Use slow-drying thinners to maintain ink fluidity on rollers.
3.Ink Replacement: Replace the ink if it has been contaminated or mixed improperly.
4.Surface Compatibility: Verify compatibility between ink and film, ensuring sufficient surface tension for proper adhesion.
5.Pressure Optimization: Adjust pressures between the rollers and cylinders, and select an appropriate anilox roller line count.
