Uyracure-180 is a cationic photoinitiator based on triarylsulfonium hexafluoroantimonate chemistry. Its chemical designation is 4-(phenylthio)phenyl diphenylsulfonium hexafluoroantimonate. The compound is supplied as a 50% active solution in propylene carbonate, with a molecular weight of 580.80 and a density of 1.420 g/cm³.
The molecular structure consists of a sulfonium cation conjugated with three aromatic rings, which disperses the positive charge and enables efficient photolysis upon UV excitation to generate polymerization-active species. This mechanism makes it suitable for initiating cationic ring-opening polymerization of epoxides, oxetanes, and vinyl ethers.
Key Characteristics
Absorption and Light Source Compatibility
The product exhibits a primary absorption wavelength of 290 nm. It is compatible with medium-pressure mercury lamps and can be used with LED light sources when combined with photosensitizers. The absorption spectrum covers the range of 250–350 nm.
Reactivity and Addition Levels
As a triarylsulfonium hexafluoroantimonate, Uyracure-180 demonstrates higher reactivity compared to phosphate-based photoinitiators. In practical terms, it achieves comparable or superior curing results at addition levels of only 40–60% of the amount required for triarylsulfonium hexafluorophosphate systems.
Curing Performance
The product supports deep curing capability, with the generated superacid (HSbF₆) able to penetrate through material thicknesses exceeding 500 μm. The cationic polymerization mechanism also exhibits low oxygen inhibition, which is particularly relevant for open-coating applications.
Temperature Stability
Uyracure-180 maintains activity across a wide temperature range from -40°C to 150°C. The decomposition temperature reaches 200°C, supporting high-temperature processing environments such as reflow soldering. Under normal temperature and light-proof storage conditions, the product maintains active stability for more than 12 months.
Non-Migration and Low Odor
The photoinitiator participates fully in the polymerization reaction, with no low molecular weight residues precipitated after curing. The photolysis process does not generate volatile byproducts. Accelerated aging tests show a yellowing index (ΔYI) of less than 1.5 after 1,000 hours, with volatile content below 0.1%.
Technical Specifications
| Parameter | Value |
|---|---|
| Chemical Name | 4-(Phenylthio)phenyl diphenylsulfonium hexafluoroantimonate |
| Molecular Weight | 580.80 |
| Density | 1.420 g/cm³ |
| Absorption Wavelength | 290 nm |
| Active Constituent | 50% in propylene carbonate |
| Viscosity at 25°C | 440 cPs |
Source: Technical data sheet
Application Areas
Transparent Coatings
The non-migration characteristic makes Uyracure-180 suitable for clear coatings where optical clarity and long-term stability are required. It is used in automotive metal paints, mobile phone hard coatings, and furniture finishes.
Adhesives and Sealants
The product supports cationic curing of adhesives, particularly in applications requiring thermal resistance and strong bonding. The post-curing behavior-where crosslinking continues after light exposure is interrupted-can be leveraged for bonding opaque materials and multi-layer applications.
LED Encapsulation
Low addition levels help minimize impact on the transmittance of encapsulation materials while improving device reliability. The low migration characteristic is particularly relevant for electronic packaging applications.
Inks
Uyracure-180 is used in cationic UV ink systems, including food packaging inks, industrial decorative inks, and electronic component marking inks. The odorless and non-migrating properties support compliance with hygiene standards for food-contact materials.
3D Printing Photoresins
The deep curing capability supports stereolithography (SLA) printing with micron-level precision. The uniform curing through material thickness helps reduce interlayer delamination risk.
Processing Considerations
Curing Temperature
For cationic UV curing products, an environment not lower than 25°C is recommended. As the temperature increases, curing reaction efficiency improves significantly. Pre-heating the substrate to 40–60°C before UV exposure can ensure efficient curing even with lower initiator loadings.
Post-Curing
Cationic polymerization does not cease immediately when the light source is removed. Crosslinking continues, with significant improvement within 1–5 minutes after illumination, reaching a relatively ideal state within 1–2 hours, and maximum curing within 2–7 days. Post-illumination heating can accelerate crosslinking speed and final cure strength.
Recommended Addition Levels
Typical addition levels range from 0.5% to 3.0% of the total formulation weight, depending on the specific system and curing requirements. The lower end of this range (0.4–1.8%) may be sufficient when utilizing pre-heating or higher curing temperatures.
Storage
Store in a tightly closed container, protected from light, at temperatures below 30°C.
Summary
Uyracure-180 is a triarylsulfonium hexafluoroantimonate photoinitiator designed for cationic UV curing applications. Its key attributes include absorption at 290 nm, higher reactivity compared to phosphate-based alternatives, reduced addition levels (40–60% of typical hexafluorophosphate systems), non-migrating behavior after cure, and thermal stability up to 200°C. The product finds use in transparent coatings, adhesives, LED encapsulation, inks, and 3D printing resins where curing performance, material cleanliness, and process reliability are required.