UV ink basic components: photosensitizer and light sensitizer
Quick answer: For practical formulation work, photoinitiator screening starts with the light source and film build, then checks yellowing, adhesion, and cure completeness under real production conditions.
Photosensitizers are molecules that absorb light energy and then transfer the energy to the photoinitiator, and return to their initial inactive state after transferring the energy.
Photosensitizer properties: photosensitizers and photoinitiators are the same point is that they can trigger the polymerization of monomers or prepolymers, the difference is that photosensitizers do not cross-linked branches in the monomer or prepolymer molecules, but will receive light energy transferred to the photoinitiator and its own reduction; add different photosensitizers can absorb a wider range of UV light or visible light and other light waves, and then the energy will be converted to the photoinitiator to promote polymerization, which can expand the light The light-sensitive range of the photoinitiator can be expanded, such as the addition of long-wavelength light-sensitive photosensitizers in dark ink can improve the curing effect of long-wave UV light to promote the curing of dark colors, large particles, masking ink.
Disadvantages: Most photosensitizers are organic compound molecules that absorb energy in the visible region, so the ink will trigger curing in visible light and is not conducive to the use and storage of ink and manufacturing, and most photosensitizers are colored or its photochemical reaction products colored not suitable for printing.
Photo-sensitizers
Photo sensitizers are molecules (usually amines) that do not absorb radiation and do not initiate polymerization, but can increase the effective rate of activity of photoinitiators.
Light sensitizer (light activator or light enhancer) characteristics: light sensitizer role is to increase the photoinitiator sensitization rate, accelerate the curing of ink. Currently often use amine sensitizer selection should pay attention to several aspects. Sensitizers are not film-forming substances are volatile, some amines such as triethylamine volatile odor is not suitable for printing inks.
A practical selection route for photoinitiator-related projects
When technical buyers or formulators screen photoinitiators, the most useful decision frame is usually cure quality plus application fit: which package cures reliably, keeps appearance acceptable, and still works under the lamp, film thickness, and substrate conditions of the actual process.
- Match the package to the lamp first: mercury lamps, UV LEDs, and visible-light systems can rank the same photoinitiators very differently.
- Check depth cure and surface cure separately: a film that feels dry on top can still be weak underneath.
- Balance yellowing with reactivity: the strongest deep-cure route is not always the best commercial choice if color or migration risk becomes unacceptable.
- Use the final formula as the benchmark: pigment load, monomer package, and film thickness can all change the apparent ranking of the same initiator.
Recommended product references
- CHLUMINIT 819: Useful when a formulation needs stronger absorption and deeper cure support.
- CHLUMINIT 1173: A practical comparison point for classic short-wave UV initiation.
- CHLUMINIT ITX: A useful long-wave support route in many printing-ink packages.
- CHLUMINIT CQ: A direct reference for visible-light and color-sensitive curing discussions.
FAQ for buyers and formulators
Why are blended photoinitiator packages so common?
Because one product may control yellowing or lamp fit well while another improves cure depth or line-speed performance, so the full package is often stronger than any single grade.
Should incomplete cure always be solved by adding more initiator?
Not automatically. The real limitation may be the lamp, film thickness, pigment shading, or the rest of the reactive system rather than simple under-dosage.
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