How to solve the water-based ink printing plate blocking?
Date: May 23 2025 From: Star Color Views:
Water-based inks are widely used for their environmental benefits and low VOC emissions. However, frequent plate blocking problems during printing can severely impact production efficiency and print quality. Plate blocking refers to the accumulation and drying of ink on the surface or cells of the printing plate, causing poor ink transfer, incomplete imprints, or blurred images. Its complex causes involve ink properties, printing processes, equipment conditions, and environmental factors, requiring systematic analysis and targeted solutions.
I. Technical Definition and Severity Assessment of Plate Blocking
1. Mechanism of Plate Blocking
- Cell Clogging: Ink drying residues, impurity particles, or pigment flocculation reduce the effective volume of cells by >20%.
- Transfer Rate Decline: Measured ink transfer rate drops from the normal 80-90% to <60% (ISO 2834 standard).
2. Severity Grading
| Grade |
Cell Clogging Rate |
Print Performance |
Cleaning Cycle Shortening |
| Level I |
10-20% |
Slight dot loss |
20% |
| Level II |
20-50% |
Blurred images, lost layers |
50% |
| Level III |
>50% |
Large-area printing failure, machine shutdown |
100% |
Detection Tools:
- Electron microscope (Zeiss EVO 18, 500× magnification)
- Laser confocal microscopy (Olympus LEXT 8000, 3D cell analysis)
II. Root Cause Analysis of Plate Blocking
1. Ink Formulation (38%)
| Component Issue |
Critical Threshold |
Failure Mechanism |
| Poor pigment dispersion |
Particle size D50 > 0.5μm |
Particles accumulate at the bottom of cells |
| Unstable resin |
Viscosity change >15% after 7 days of storage |
Cross-linking substances precipitate to form gels |
| Poor additive compatibility |
Surface tension difference >5mN/m |
Reduced wettability causes dry ink residues |
2. Printing Process (29%)
- Excessive Drying: Hot air temperature >55°C increases cell mouth skinning risk by 400%.
- pH Fluctuation: Deviation from 8.5-9.5 (±0.3) triggers resin flocculation.
- Inappropriate Viscosity: Ford #4 cup measurement >45s or <25s (ideal 30-40s).
3. Inadequate Equipment Maintenance (18%)
- Doctor blade pressure deviation >0.5Bar (standard 1.5-2.5Bar).
- Anilox roll cleanliness <95% (residual ink >0.1g/m²).
- Ink stagnation in dead corners of the ink path (no circulation for 4 hours).
4. Environmental Interferences (15%)
| Parameter |
Safe Range |
Consequences of Exceeding Standard |
| Workshop temperature |
20-25°C |
>28°C → Drying rate ↑30% |
| Relative humidity |
50-65%RH |
<40% → Static electricity adsorbs impurities ↑ |
| Dust concentration |
<1mg/m³ (PM10) |
>5mg/m³ → Cell clogging rate ↑50% |
III. 6 Systematic Solutions
1. Ink Formulation Optimization (Core Measure)
| Improvement Direction |
Technical Solution |
Parameter Standard |
| Enhanced pigment dispersion |
Nano bead milling (0.3mm zirconia beads) |
D50 ≤0.3μm, PDI <1.2 |
| Resin system reconstruction |
Acrylic-polyurethane hybrid (Tg=65°C) |
Storage stability >6 months |
| Scientific additive formulation |
0.3% wetting agent + 0.1% defoamer |
Dynamic surface tension ≤32mN/m |
| Experimental data: After optimization, ink transfer rate increased from 68% to 87%, and blocking interval extended by 4 times. |
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2. Precise Process Parameter Control
- Drying gradient: Three-stage temperature (50°C→65°C→45°C), airspeed 15/20/18m/s.
- pH closed-loop regulation: Automatic titration system (±0.1 accuracy), replacing AMP-95 with ammonia water for stability.
- Viscosity management: Online rotational viscometer (Brookfield DV3T), fluctuation <±2%.
3. Intelligent Equipment Upgrades
- Ultrasonic doctor blade: 40kHz high-frequency vibration, cleaning rate increased to 99.8% (vs. 92% for traditional blades).
- Self-cleaning ink path: Automatic circulation mode during shutdown (flow rate 0.5m/s, anti-sedimentation).
- Anilox roll coating: Ceramic coating (hardness HV1300) for wear resistance, lifespan extended by 3 times.
4. Environmental Control Standards
| Equipment |
Control Parameters |
Effect Verification |
| Temperature/humidity control unit |
23±1°C / 60±3%RH |
Blocking rate ↓40% |
| Static elimination bar |
Ionization voltage 6-8kV |
Dust adsorption ↓70% |
| Fresh air filtration system |
H13 HEPA + activated carbon |
Particles >0.3μm removed 99.97% |
5. Preventive Maintenance System
- Daily Inspections:
- Doctor blade angle (55-65°) and pressure (1.8-2.2Bar) calibration.
- Cleaning of ink pump filter (200-mesh stainless steel screen).
- Weekly Maintenance:
- Anilox roll depth detection (error <±2μm).
- CIP cleaning of ink path (pH=10.5 alkaline cleaner).
6. Emergency Handling Procedure for Plate Blocking
Shutdown → Seal ink path → Soak in specialized cleaning agent (15min) → High-pressure washing (50Bar) → Soft brush cleaning → Air knife drying
IV. Industry Case Studies
Case 1: Efficiency Improvement in a Flexible Packaging Printing Factory
- Problem: Plate blocking caused downtime every 2 hours during PE film printing, resulting in monthly losses of ~$25,000.
- Solutions:
- Added 0.2% dispersant to the ink, reducing average pigment particle size from 0.7μm to 0.25μm.
- Installed an ink path temperature control system, maintaining ink temperature at 25±0.5°C.
- Switched to laser-engraved ceramic anilox rolls (1200LPI) for uniform ink transfer.
- Outcomes: Blocking issues virtually eliminated (rare occurrences after 8 hours of printing), annual efficiency gain of $287,671.
The above is about water-based ink in the printing of the blocking willingness and solutions, if you are using water-based ink also encountered such problems, welcome to contact us, looking forward to solving the problem for you!
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