Risposta rapida: Start with Fotoiniziatore 184 when you need a practical benchmark for routine low to medium-thickness UV coatings, inks, or adhesives. Move Fotoiniziatore 1173 higher on the shortlist when liquid handling, blendability, and lower-yellowing clear systems matter more. Push Fotoiniziatore 819 forward when the system is thicker, more pigmented, or harder to cure through.
That is the practical commercial split. These three photoinitiators sit in the same buying conversation, but they should not be treated as interchangeable.
Side-by-side shortlist: 184 vs 1173 vs 819
| Prodotto | Best first fit | Why buyers shortlist it | When it is not the first option |
|---|---|---|---|
| Fotoiniziatore 184 | Routine low to medium-thickness UV coatings, inks, and adhesives | Type I free-radical route, strong 365 nm relevance on the current Longchang page, and a practical benchmark for fast curing in clear or lighter-color systems | When the main problem is deep cure, heavy pigmentation, or a broader-response curing window |
| Fotoiniziatore 1173 | Clear acrylic varnishes and formulation programs that benefit from liquid handling | Liquid form, easy blending, good compatibility, and lower-yellowing positioning for acrylic UV-curable varnishes on paper, metal, and plastic | When the system is thick, optically difficult, or under stronger through-cure pressure |
| Fotoiniziatore 819 | Thicker coatings, pigmented systems, and LED-related screening | Broad 370 to 450 nm absorption positioning, deep-cure support, and stronger fit for pigmented or harder-to-cure systems | When the job is a simple thin clear system and deeper-cure power is not the main bottleneck |
If you need the broader family view first, start with Longchang’s photoinitiator selection guide.
When Photoinitiator 184 is the better fit
184 is the most useful first benchmark when the job is conventional free-radical UV curing and the team wants a familiar starting point.
- Routine coatings and inks: Longchang positions it across wood, plastic, metal, paper, multiple printing-ink routes, and UV-curable adhesives.
- Low to medium film thickness: the current product page ties 184 to fast curing in low to medium-thickness coatings, inks, and glues.
- Clear or lighter-color systems: the current page also emphasizes low yellowing and use in transparent or lighter-color applications.
If you are screening a UV formulation and need the fastest practical reference point, 184 is often the right first sample.
When Photoinitiator 1173 is the better fit
1173 deserves earlier attention when the project benefits from liquid handling, easier blending, and lower-yellowing performance in acrylic UV-curable systems.
- Liquid handling convenience: Longchang describes 1173 as a liquid photoinitiator, which can simplify formulation work compared with solid alternatives.
- Clear coatings and varnishes: the current page recommends it for acrylic UV-curable varnishes on paper, metal, and plastic surfaces, especially where only slight yellowing is needed after long sunlight exposure.
- Blend flexibility: Longchang also states that 1173 has good compatibility and can be easily mixed with other photoinitiators and prepolymers.
If the buyer is working on a clear or color-sensitive acrylic system, 1173 is often a better commercial reference than a purely routine benchmark.
When Photoinitiator 819 is the better fit
819 should move up the shortlist when the project is no longer a simple thin-film screening job.
- Deeper cure demand: Longchang’s current page highlights deep curing and a bleaching effect that helps light penetration.
- Pigmented or optically difficult systems: the same page positions 819 for pigmented systems, thick coatings, and harder curing conditions.
- Broader-response and LED-related work: Longchang also presents 819 as suitable for UV-LED light sources and broader-response curing windows.
- Thicker sections: 819 is positioned for thick coatings and deeper-section curing where weaker candidates may lose performance.
If the job involves pigmented UV inks, thick sections, or harder through-cure problems, 819 usually deserves earlier sampling than 184 or 1173. Readers working specifically on ink systems can also review this UV inks guide.
How buyers should choose before sampling
1. Match the curing source first
Start with the lamp and wavelength window. If the photoinitiator does not fit the real curing source, the rest of the comparison becomes noisy.
2. Judge film thickness honestly
Thin clear layers and thicker pigmented sections should not use the same default shortlist.
3. Check pigment load early
Pigment often changes the ranking quickly because it reduces light penetration and raises through-cure pressure.
4. Decide how sensitive the system is to yellowing
If appearance matters, the lower-yellowing positioning of 184 and 1173 becomes more important.
5. Keep formulation practicality in scope
Physical form and blending behavior still matter. A liquid product with easier handling can shorten development time.
For a coating-focused selection workflow, also see Selection of Photoinitiators in UV Coating Formulations. If the buyer is still deciding between curing mechanisms first, the live comparison of free-radical and cationic photoinitiator routes is the better starting point.
Recommended Longchang product paths
- Routine free-radical benchmark: Fotoiniziatore 184
- Liquid low-yellowing acrylic route: Fotoiniziatore 1173
- Deep-cure and pigmented-system route: Fotoiniziatore 819
- Broader selection guide: How to choose a photoinitiator for UV curing
- Related coating article: Selection of Photoinitiators in UV Coating Formulations
- Related chemistry comparison: Cationic vs free radical photoinitiator
FAQ
Is Photoinitiator 184 or 1173 better for clear coatings?
Both can be relevant, but 1173 deserves stronger consideration when liquid handling, blending convenience, and low-yellowing behavior in acrylic UV-curable varnish systems matter more. 184 remains a practical benchmark for routine UV-curing work.
When should I move from 184 or 1173 to 819?
Move 819 higher in the shortlist when the project needs more support for thicker films, pigmented systems, deeper cure, or UV-LED-related curing windows.
Which product is stronger for pigmented UV inks?
Based on the current Longchang product positioning, 819 is the stronger first review point when pigment load and deeper cure become the main concern.
Can 184, 1173, and 819 be used in blends?
Longchang’s current product pages indicate blending logic is relevant in this family, especially for 1173, and the 184 and 819 pages also discuss combination use. Final blend choice should still follow the actual curing window, formulation system, and sample results.
Need help narrowing the shortlist?
If your UV coatings, inks, or adhesives project is limited by yellowing, cure depth, pigment load, or lamp fit, define the real bottleneck first and then compare 184, 1173, and 819 against that constraint. Longchang can then help narrow the most relevant product path and sample set.