Risposta rapida: In UV screen ink, the best photoinitiator is the one that matches the real ink film and pigment challenge, not the one with the broadest generic ink description. Fotoiniziatore TPO deserves early attention when the formulation needs deeper cure, lower yellowing, and stronger relevance to white or high-pigment systems. Fotoiniziatore 369 is a strong first review point when the real job is dark-color, opaque, or more difficult screen-ink curing. Fotoiniziatore DETX moves up when the buyer wants a long-wave route with visible-light or LED relevance and is willing to build the package correctly with a co-initiator.
That is the useful commercial split. UV screen ink selection becomes much cleaner when buyers compare pigment load, film build, cure-through pressure, and lamp fit first instead of treating all photoinitiators as interchangeable names.
Why UV screen ink needs a tighter shortlist
Screen-printing jobs often punish weak photoinitiator selection faster than a generic UV-ink article suggests. The deposit is frequently heavier, the color can be darker or more opaque, and the buyer usually cares about several things at once:
- Film build and cure-through: the surface can look acceptable while deeper cure still lags.
- Pigment burden: white, black, and high-opacity colors change how much light reaches the lower part of the film.
- Lamp fit: conventional UV and LED-centered setups do not always reward the same shortlist.
- Appearance pressure: yellowing control still matters, especially in white or light-colored work.
- Formulation design: some routes need a simple Type I starting point, while others need a Type II package with a co-initiator.
That is why a short disciplined first sample round is usually more useful than a long generic list.
If you need the broader family view first, start with Longchang’s photoinitiator selection guide.
Quick shortlist: TPO vs 369 vs DETX for UV screen ink
| Prodotto | Best first fit | Why buyers shortlist it | When it is not the first option |
|---|---|---|---|
| TPO | White, high-pigment, or deeper-curing screen inks where low yellowing also matters | Longchang explicitly lists screen-printing inks, colored systems, deep curing, low yellowing, and preference for white or high-pigment systems on the current TPO page | When the job is mainly a dark-color screen-ink route or when the buyer specifically wants a long-wave Type II package around an amine co-initiator |
| 369 | Dark-color, opaque, or more difficult screen inks that need stronger long-wave help | Longchang explicitly positions 369 for screen-printing inks, dark-color systems, and deeper or pigmented cure, with a recommended screen-ink route of 2 to 4% 369 plus 1 to 3% 184 | When the buyer’s first concern is white-system yellowing control or a LED-leaning Type II route |
| DETX | Long-wave, visible-light, or LED-oriented screen-ink packages that can use a co-initiator | Longchang positions DETX for screen-printing inks, long-wave absorption near 385 nm, response to 405 nm and 420 nm LEDs, and good performance in colored systems and thicker films | When the team wants the simplest single-product starting point instead of a Type II route that must be built with tertiary amines or another co-initiator package |
When TPO is the better fit
TPO deserves early review when the buyer is trying to protect cure-through and appearance at the same time.
- Screen-ink relevance is explicit: Longchang directly lists screen printing inks on the TPO page.
- High-pigment and white-system logic is direct: the same page supports colored systems, deep curing, and preference for white or high-pigment systems.
- Yellowing control matters: Longchang also supports low yellowing and low odor positioning for TPO in these UV-curing applications.
- Thicker-film logic is already part of the product story: the page repeatedly frames TPO around thick films and deeper cure.
If the screen ink is white, highly pigmented, or being evaluated partly on appearance stability, TPO usually deserves one of the earliest sample positions.
When 369 is the better fit
369 moves ahead when the job stops behaving like an easy clear or lightly pigmented screen ink.
- Screen-printing support is direct: Longchang explicitly lists screen printing inks on the 369 page.
- Dark-color fit is stronger: the same page says 369 is particularly suitable for dark color systems such as blue and black.
- Opaque and deeper-cure logic is already established: Longchang positions 369 for deeper or pigmented curing and long-wave UV capture around 350 to 380 nm.
- There is even a packaged screen-ink starting point: the current page recommends 2 to 4% 369 plus 1 to 3% 184 for screen inks.
That makes 369 especially useful when the buyer is not just screening a routine ink, but trying to solve a darker or optically harder screen-print route. If you need the companion benchmark product in that package, see Fotoiniziatore 184.
When DETX is the better fit
DETX should move up when the buyer wants a more deliberate long-wave route instead of a simple one-product benchmark.
- Screen-printing relevance is explicit: Longchang directly lists screen printing inks on the DETX page.
- LED and visible-light relevance are stronger: the page supports peak absorption around 385 nm and response to 405 nm and 420 nm LEDs.
- Thicker-film and colored-system value are already part of the positioning: Longchang supports DETX for colored systems, white coatings, and thicker films.
- Package design matters: Longchang also makes clear that DETX is a Type II route that needs a co-initiator such as a tertiary amine to generate radicals efficiently.
If the buyer is building an LED-oriented screen-ink package or wants a longer-wave support route for a harder film, DETX can be a very practical shortlist item. It is simply better treated as a package design decision, not as a drop-in replacement for every Type I benchmark.
How buyers should choose before requesting samples
1. Start with the real color and opacity problem
White, light, dark, and highly opaque screen inks should not all use the same first shortlist.
2. Keep film build visible
A heavier screen-ink deposit changes the cure-through problem. Do not judge the package only by surface feel.
3. Separate Type I and Type II logic
TPO and 369 can be reviewed as direct radical routes. DETX needs to be evaluated as a Type II package with the right co-initiator support.
4. Match the lamp first
If the line is leaning toward 405 nm style LED selection, the shortlist should show that from the first sample round.
5. Keep the first trial round tight
A better commercial answer usually comes from comparing two or three well-matched routes rather than screening a long speculative list.
If the printing project is closer to narrow-web packaging work, continue with Photoinitiator for UV Flexo Ink. If the line is moving toward broader LED selection logic, see Photoinitiator for UV LED Curing.
Recommended Longchang product and article paths
- White or high-pigment deep-cure route: Fotoiniziatore TPO
- Dark-color and opaque screen-ink route: Fotoiniziatore 369
- Long-wave LED-oriented route: Fotoiniziatore DETX
- Companion benchmark in screen-ink blends: Fotoiniziatore 184
- Related packaging-printing article: Photoinitiator for UV Flexo Ink
- Broader family guide: How to Choose a Photoinitiator for UV Curing
FAQ
Which photoinitiator is best for UV screen ink?
There is no single best answer. TPO usually deserves early attention for white or high-pigment deep-cure work, 369 is a stronger route for darker or opaque screen inks, and DETX becomes more relevant when the buyer wants a long-wave LED-oriented package with a co-initiator.
Why is UV screen ink selection different from a generic UV ink article?
Because screen-printing jobs often carry a heavier film build and a tougher cure-through problem, especially in opaque, white, or dark-colored systems.
When should I choose 369 instead of TPO?
Choose 369 earlier when the real issue is dark-color or more opaque screen-ink curing and you want a route Longchang already positions for those systems.
When should DETX move up the list?
Move DETX up when the line is more LED-oriented, longer-wave response matters, and the team is willing to build a proper Type II package with a co-initiator.
Need a tighter shortlist for UV screen ink?
If your project is being limited by pigment burden, film build, cure-through, or LED fit, define the real bottleneck first and then compare only the most relevant Longchang routes. That usually gives a cleaner sampling decision than comparing photoinitiator names without an application frame.