What is uv printing?
Date: Sep 04 2024 From: Star Color Views:
I. Definition and Core Principles of UV Printing
1. Technical Definition
UV printing (Ultraviolet Printing) is a digital printing technology that uses ultraviolet (UV) energy to instantly cure inks or coatings. Unlike traditional printing, which relies on solvent evaporation or oxidation drying, UV printing triggers a chain polymerization reaction of monomers and oligomers in the ink through photoinitiators absorbing specific wavelengths of ultraviolet light. This leads to complete curing within 0.1 - 5 seconds and the formation of a highly cross - linked solid film.
2. Photocuring Reaction Mechanisms
(1) Free Radical Polymerization System
Photoinitiators: Such as benzophenone (BP), 1 - hydroxycyclohexyl phenyl ketone (184)
Reaction Pathway:
PIhνPI∗→Free Radicals+Monomers→Polymers
Characteristics: Fast curing speed (> 200 m/min), but easily inhibited by oxygen.
(2) Cationic Polymerization System
Photoinitiators: Sulfonium salts (e.g., CPI - 210S)
Reaction Pathway:
PIhνH+(Acid)+Epoxy Monomers→Three - Dimensional Network Structure
Characteristics: Strong deep - curing ability, no oxygen inhibition, and suitable for thick ink layers.
II. Six Major Technical Advantages of UV Printing
1. Efficiency Breakthrough
| Parameter |
UV Printing |
Traditional Solvent Printing |
| Drying Time |
0.5 - 3 seconds |
2 - 24 hours |
| Printing Speed |
150 - 300 m/min |
100 - 300 m/min |
| Equipment Footprint |
40% reduction |
- |
2. Exceptional Printing Quality
- Resolution: Up to 400 LPI (1.6 times that of offset printing).
- Color Gamut: Pantone color card coverage > 95%.
- Three - Dimensional Effects: Local UV varnishing can achieve 5 - 100 μm embossed textures.
3. Revolutionary Material Versatility
| Substrate Type |
Application Cases |
Key Technical Solutions |
| Plastic Films (PET/BOPP) |
Food packaging labels |
Low - temperature curing (below 50°C) |
| Metals (Aluminum foil/Tinplate) |
Aluminum can printing |
Cationic UV inks resistant to 200°C |
| Glass/Ceramics |
Electronic product touch panels |
Nanoscale UV inks + high - energy LED curing |
4. Environmental Protection and Sustainability
- VOC Emissions: Close to zero (VOC content in traditional solvent - based inks is 300 g/L).
- Energy Efficiency: 60 - 70% more energy - saving than thermal curing systems.
- Circular Economy: 100% solid content with no solvent residue, and waste can be recycled.
III. Core Components and Technical Parameters of UV Printing Systems
1. Light Source Systems
| Type |
Wavelength Range (nm) |
Power Density (W/cm) |
Lifespan (h) |
Application Scenarios |
| Mercury Lamps |
200 - 450 |
120 - 200 |
800 - 1,500 |
General printing |
| LED - UV |
365/385/395/405 |
80 - 150 |
20,000+ |
Heat - sensitive materials/fine printing |
| Excimer Lamps |
172/222/308 |
300 - 500 |
5,000 |
Ultra - high - speed curing |
2. Ink Systems
| Component |
Function |
Typical Proportion |
Performance Impact |
| Monomers |
Regulate viscosity/reactivity |
40 - 60% |
Curing speed/hardness |
| Oligomers |
Determine film physical properties |
30 - 50% |
Adhesion/flexibility |
| Photoinitiators |
Trigger photochemical reactions |
3 - 8% |
Curing depth/yellowing |
| Additives |
Leveling/defoaming/wear resistance |
1 - 5% |
Printing adaptability/durability |
3. Intelligent Control Systems
- Energy Closed - Loop Feedback: Real - time monitoring of UV intensity (unit: mJ/cm²) and automatic adjustment of lamp power.
- Oxygen Concentration Management: Nitrogen inert environment (O₂ < 200 ppm) to improve surface curing effects.
- Digital Workflow: CIP3/CIP4 data presetting reduces color calibration time by 50%.
IV. Industrial Application Matrix of UV Printing
1. Packaging and Printing Field
- Food and Beverage:
- Boil - resistant labels (121°C/30 min).
- High - barrier shrink films (oxygen permeability < 5 cc/m²·day).
- Consumer Electronics:
- Mobile phone IMR films (10μm ultra - thin printing).
- Light guide plate dot printing (precision ±2μm).
2. Industrial Manufacturing Field
- Automotive Components:
- Dashboard IMD in - mold decoration.
- UV white paint for car headlight reflectors (reflectivity > 95%).
- Building Materials and Decoration:
- Wood grain transfer printing (weatherability ΔE < 3@1,000h).
- Metal brushing effect printing (Ra = 0.8 - 1.6μm).
3. Emerging Application Scenarios
- Biomedical:
- Sterilizable medical device markings (ethylene oxide resistant).
- Hydrophilic/hydrophobic patterns on microfluidic chips (contact angle precision ±2°).
- Smart Wearables:
- Flexible circuit printing (line width/spacing = 20/20μm).
- Tactile feedback coatings (modulus gradient design).
V. Challenges and Solutions in UV Printing
1. Technical Bottleneck Breakthroughs
| Challenge |
Innovative Solutions |
Commercial Cases |
| Difficult Deep Curing |
Dual curing systems (UV + heat/moisture) |
3D printing of tire molds (curing depth > 5mm) |
| Yellowing Issues |
Benzotriazole - type UV absorbers (< 0.3% addition) |
High - end cosmetic packaging (b* value < 1.5) |
| High Equipment Investment |
Modular LED - UV systems (40% cost reduction) |
Small and medium - sized label printing factories (ROI < 18 months) |
2. Environmental Compliance Upgrades
- Photoinitiator Replacement: Phase out migratory substances like ITX/BP and adopt low - migration TPO .
- Circular Production Systems: Waste ink recycling rate > 85% (filtration + redispersion process).
- Mercury Lamp Replacement Plan: Mandatory phase - out of mercury lamps by the EU RoHS Directive in 2025.
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