Buying Photoinitiator 184: What Matters
Photoinitiator 184 (CAS 947-19-3, 1-hydroxycyclohexyl phenyl ketone) is a mainstream UV photoinitiator, but buying well means confirming the identity, checking the purity and colour that drive cure performance, matching the grade to the application, and understanding that in many modern systems it will be used in a blend rather than alone.
For the chemistry behind these points, see our main article on photoinitiator 184 (CAS 947-19-3).
Step 1: Confirm the Identity
Photoinitiator 184 is 1-hydroxycyclohexyl phenyl ketone; Irgacure 184 and Omnirad 184 are trade names for the same substance. Confirm the CAS number (947-19-3) and that the product is the alpha-hydroxyketone, not a different photoinitiator or a blend without being told so.
Step 2: Read the Specification
| Parameter | Why it matters | Typical value |
|---|---|---|
| Appearance | Confirms a clean white powder/flake | White crystalline powder |
| Purity (GC) | Drives cure efficiency | ≥ 98.00% |
| Melting range | Identity and purity; also handling | 45.0–50.0 °C |
| Loss on drying | Moisture / volatile content | ≤ 0.50% |
| Colour | Affects appearance of clear films | Low colour |
Purity and colour are the two parameters that most affect performance in clear systems: a low-purity or off-colour batch cures less efficiently and can tint a clear coating.
Step 3: Match the Grade and Form
- Standard grade. The white crystalline powder/flake for general UV coatings and inks.
- Low-migration / high-purity grade. For packaging, medical or other sensitive uses requiring migration data and appropriate approvals.
- Blends. 184 is often supplied blended with TPO or 127; confirm the composition and the active content.
- Pre-dispersed form. For water-based or difficult-to-incorporate systems.
Step 4: Check the Application Fit
Because 184 absorbs mainly in the UV-B/C and weakly above about 300 nm, its suitability depends on the system:
- Clear, thin films and typical mercury-lamp curing: an excellent fit.
- Pigmented, filled or thick films and UV-LED curing: expect to use 184 together with a red-shifted initiator such as TPO.
- Low-migration applications: consider photoinitiator 127, or a validated low-migration system.
Supplier Checklist
- Identity. CAS 947-19-3 and the correct substance confirmed.
- Purity and colour. GC purity and colour within specification.
- Grade and form. Standard, low-migration or blend, matched to your process.
- Documentation. SDS, per-batch COA and, where relevant, food-contact/migration statements.
- Storage. Cool, dry, light-protected storage, given its low melting point.
- Consistency. Batch history if colour or purity is critical.
Common Buying Mistakes
- Buying on price alone. A cheaper, off-colour or lower-purity batch can spoil a clear coating and cure poorly.
- Assuming one initiator fits all. 184 on its own will underperform in pigmented or LED-cured systems.
- Ignoring migration for packaging. Food-contact uses require the right grade and migration data.
- Poor storage. Its low melting point makes it prone to caking; keep it cool and dry.
- Overlooking blends. If you expect pure 184 and receive a blend (or vice versa), the dosing and performance change.
How PolyBlueChem Can Help
PolyBlueChem can supply photoinitiator 184 (CAS 947-19-3) as a bulk raw material, with the documentation appropriate to your application. We can provide current specifications and a COA, discuss the grade and form that fit your system, and quote packaging and shipping options. To request specifications, a sample or a quotation, contact the PolyBlueChem team.
Frequently Asked Questions
What should I look for when buying photoinitiator 184?
Confirm the identity (CAS 947-19-3), check the GC purity and colour, match the grade and form to your application, and secure the SDS, COA and any migration statements.
Is Irgacure 184 the same as photoinitiator 184?
Yes; Irgacure 184 (and Omnirad 184) are trade names for 1-hydroxycyclohexyl phenyl ketone.
Do I need a low-migration grade?
If the cured film is intended for food packaging or other sensitive uses, yes — confirm the grade and the migration data for your application.
What documents should come with a shipment?
At minimum a safety data sheet and a per-batch certificate of analysis; food-contact/migration statements where applicable.
How should photoinitiator 184 be stored?
Cool, dry and protected from light, since it melts at about 45–50 °C and can cake if warm.