In the coatings, inks and packaging industries, the photocuring efficiency of colored systems (such as those containing titanium dioxide, carbon black and other pigments) is limited by the absorption and scattering of ultraviolet light by the pigments, resulting in insufficient deep curing. Photoinitiators for Pigmented Systems have become the key material to break through this bottleneck through spectral adaptation, nano-enhancement and synergistic enhancement technologies. This article analyzes how it promotes efficient production and green transformation in the chemical industry from the perspectives of technical challenges, solutions, application scenarios and market trends.
1. Core Challenges of Colored System Photocuring
The presence of pigments significantly affects the performance of photoinitiators, as shown in the following:
Spectral competitive absorption: For example, titanium dioxide (TiO₂) has strong light absorption in the 200-400nm band, which overlaps with the absorption peak of conventional photoinitiators (such as benzil derivatives), reducing the utilization rate of light energy1.
Light scattering effect: Pigment particles limit the penetration depth of light, and the thickness of the cured layer is usually <50μm, which is difficult to meet high hiding requirements.
Intensified oxygen inhibition: The pigment surface absorbs oxygen, inhibiting the growth of free radical chains, causing surface stickiness or incomplete curing.
2. Technological breakthroughs in colored system photoinitiators
1. Spectral adaptation initiators
Long wavelength photoinitiator: Camphorquinone (absorption peak 450-500nm) is compounded with amines (such as DMAB) to avoid the strong absorption area of TiO₂ and achieve visible light curing, which is suitable for white coatings and packaging inks.
Bimolecular synergistic system: Benzophenone is combined with tertiary amines (such as triethanolamine) to improve quantum efficiency through energy transfer mechanism and adapt to high-concentration carbon black system.
2. Nano-enhanced technology
Nano-particle loading: Silica-coated photoinitiator (particle size ≤ 50nm) can reduce light scattering, increase ultraviolet penetration depth by more than 30%, and the thickness of the cured layer exceeds 100μm.
Core-shell structure design: The outer layer of the photoinitiator is coated with a transparent resin (such as polyurethane acrylate) to reduce direct contact with the pigment and reduce energy loss.
3. Synergistic system
Dual curing mechanism: UV/thermal dual curing initiator (such as TPO-L and peroxide compound) solves the penetration problem of high pigment content system by light curing surface and heat curing deep layer.
Antioxidant inhibitor additive: Phosphorus or sulfur compounds (such as TPO) can remove oxygen, improve surface curing efficiency, and hardness up to 4H (pencil hardness).
3. Industry applications and typical cases
Automotive coatings
For high-hiding metallic basecoat, curing time <30 seconds, weather resistance passed 2000-hour QUV test, color difference ΔE≤1.5.
Printing inks
Carbon black ink suitable for screen printing, photoinitiator addition reduced by 20%, curing speed increased to 10m/min (365nm LED light source).
Electronic product housing coating
White UV coating containing TiO₂ passed 5B grade adhesion test (ASTM D3359), alcohol wiping resistance >500 times.
4. Production process and environmental innovation
Water-based technology
Development of water-based photoinitiators (such as IRGACURE 2959), VOC emissions <50ppm, in line with EU REACH and GB 33372-2020 standards.
Intelligent production control
Use AI algorithm to optimize the initiator particle size distribution (PDI <0.1), and improve batch stability by 25%.
Application of bio-based raw materials
Use epoxidized soybean oil to modify the photoinitiator, with a biomass content of ≥30%, and a 40% reduction in carbon emissions, which is in line with the carbon neutrality goal.
5. Customized services and sample support
We provide full-scenario solutions for Photoinitiators for Pigmented Systems, including:
Free sample application: Support 500g small batch trial production, adapt to your pigment type (TiO₂, carbon black, etc.) and light source parameters (LED/mercury lamp).
Technology collaborative development: Customize formulas based on curing speed (seconds to minutes), weather resistance (QUV aging test) or environmental protection requirements.
Global compliance certification: The product has passed RoHS, REACH and FDA food contact material certification, helping to quickly enter the export market.
