I. Adhesion Failure (Cross-Cut Test <3B)

Failure Mechanism:
Mismatch between PET surface energy (38–42mN/m) and water-based ink surface energy (45–50mN/m) leads to contact angle >65°.

Solutions:

1. Substrate Pretreatment
   • Corona treatment: Dyne level increased to 54–56mN/m (power 8–10kW, speed 80m/min).
   • Primer coating: Water-based polyesterurethane primer (dry film thickness 0.8–1.2μm).
2. Ink Formulation OptimizationComponentSpecificationFunctionModified polyurethane dispersionShore A 75–80 hardnessMain film-forming resinEpoxy-grafted acrylate8–12% additionCrosslinking enhancementCarbodiimide-based crosslinker0.5–1.5% (post-cure at 60℃)Chemical bond reinforcementResult: Cross-cut test achieved 5B (ASTM D3359).

II. Low Drying Efficiency (Energy Consumption >1.8kW·h/kg)

Issue Analysis:
Latent heat of evaporation for water-based systems (2257kJ/kg) is 2.3× higher than solvent-based inks.

Efficiency Improvement:

Technology	Parameters	Energy Saving
Infrared-hot air drying	80℃/5s → 110℃/8s	40% energy reduction
Microwave-assisted drying	2450MHz/300W	2.5× faster drying
Cosolvent optimization	2–3% diethylene glycol butyl ether	35% evaporation rate increase

III. Printing Levelling Defects (Orange Peel Index >0.25)

Root Cause:
Dynamic surface tension >32mN/m results in spreading coefficient <0.8.

Improvements:

1. Rheology Control Agents
   • Hydrophobically modified alkali-swellable thickener (HASE) at 0.3–0.6%.
   • Thixotropy index controlled at 1.8–2.2 (Brookfield DV3T).
2. Process Optimization
   • Printing viscosity: Flexo 18–22s / Gravure 12–15s (Ford Cup, 25℃).
   • Environmental control: 25±2℃, 55±5% RH.

IV. Poor Resistance (Ethanol Rubs <20)

Enhancement Strategies:

Approach	Components	Performance Outcome
Chemical crosslinking	Silicone-modified polyurethane (15%) + aziridine crosslinker (0.8–1.2%, pH 8.5–9.0)	Ethanol rubs >200 (GB/T 13217.7)
Physical reinforcement	Nano SiO₂ aerogel (3–5%)	Abrasion resistance ×4

V. Static Electricity Buildup (Surface Resistance >10¹³Ω)

Safety Risk:
Static voltage up to 15kV poses fire hazard (NFPA 77).

Anti-Static Solutions:

1. Ink Modification
   • Ionic liquid-based antistatic agent (0.5–1.0%, resistivity <10⁹Ω·□).
   • Carbon nanotubes (0.3–0.5%, volume resistivity 10³Ω·cm).
2. Equipment Upgrades
   • Install static eliminators (±5kV balance control).
   • Grounding system impedance <4Ω (IEC 61340).

VI. Color Variation (ΔE >2.0)

Control System:

1. Pigment Standardization
   • Particle size D90 <1μm (laser diffraction).
   • Color concentration variation <±1.5% (spectrodensitometer).
2. Process Monitoring
   • Online colorimeter (30cm interval, feedback to ink supply).
   • Automatic viscosity compensation (±0.5s tolerance).

VII. Laminating Strength Degradation (Peel Force <1.5N/15mm)

Preventive Measures:

1. Interface Strengthening
   • Primer-type water-based adhesive (3.5–4.5g/㎡ coating).
   • Plasma treatment (1000W power, 20m/min speed).
2. Ink Compatibility
   • Avoid direct contact between carboxyl-containing resins and amine-based curing agents.
   • Curing conditions: 50℃/48h, 60% RH.