In the rapidly evolving world of UV-curable coatings, adhesives, and photoresists, the choice of photoinitiator can determine print resolution, cure speed, and final product performance. SINOCURE® BCIM (2,2′-Bis(2-chlorophenyl)-4,4′,5,5′-tetraphenyl-1,2′-biimidazole, CAS 7189-82-4) is a highly efficient hexaarylbiimidazole (HABI)-type photoinitiator designed for demanding UV polymerization applications.
As a leading supplier of specialty photoinitiators, SINOCURE® BCIM offers a unique combination of high reactivity, excellent thermal stability, and superior compatibility with electronic-grade and visible-light-curing systems.
SINOCURE® BCIM belongs to the hexaarylbiimidazole (HABI) family of photoinitiators. Upon exposure to UV radiation, the HABI molecule cleaves reversibly to form triarylimidazolyl (lophyl) radicals. These radicals initiate the free-radical polymerization of acrylate monomers and oligomers. This mechanism enables both rapid surface cure and deep‑section polymerization in a variety of UV and LED curing systems.
SINOCURE® BCIM exhibits excellent chemical stability, good solubility in common monomers and solvents, and a high decomposition temperature, making it compatible with a wide range of formulation components.
Property | Specification |
Appearance | Yellow crystalline powder |
Assay (HPLC) | ≥99.0% |
Melting point | 195 – 205°C |
Loss on drying | ≤0.5% |
Ash content | ≤0.1% |
CAS No. | 7189-82-4 |
Molecular formula | C₄₂H₂₈Cl₂N₄ |
Molecular weight | 659.6 |
UV max absorption | ~264 nm (can be sensitized for visible light) |
Data based on typical test results. For COA, please request from our technical team.
Unlike conventional photoinitiators such as α‑hydroxy ketones (e.g., 1173) or acylphosphine oxides (e.g., TPO, 819), HABI-type initiators utilize a unique reversible radical generation mechanism.
Upon UV exposure, HABI undergoes a photochemical cleavage to produce two triarylimidazolyl radicals. These radicals are highly stable due to delocalization across the imidazole ring and the surrounding aromatic system. They can either:
Directly initiate free‑radical polymerization of acrylate groups
Interact with hydrogen donors or chain transfer agents to produce additional initiating species
Importantly, the radical recombination back to HABI is reversible in the absence of light, providing excellent dark stability and long pot life in formulated systems.
BCIM is widely recognized as a high-performance photoinitiator for printed circuit board (PCB) photoresists, dry film resists, and graphic arts applications. Studies have demonstrated that BCIM-based initiating systems can substitute conventional 907/ITX systems commonly used in PCB photoresists.
While BCIM has a main UV absorption peak at ~264 nm, it can be efficiently sensitized by suitable dye molecules for longer-wavelength exposure including 365 nm, 405 nm, and even visible light.
Common photosensitizers include:
EMK (N,N-bis(diethylamino)benzophenone)
Visible light sensitizer)
Cyanine dyes and cyclopentanone/cyclohexanone dyes
When combined with a dye sensitizer and a hydrogen donor (e.g., NPG, thiols), BCIM forms a highly efficient three-component photoinitiating system suitable for visible light laser imaging applications.
Because HABI radicals recombine back to the original dimer in the dark, BCIM offers low residual extractables and excellent migration resistance compared to some one-way cleavage initiators. This is particularly important for food packaging, electronic encapsulation, and medical applications.
Application | Description |
PCB Liquid Photoresist | |
Dry Film Photoresist | Excellent pattern definition and adhesion, suitable for 405 nm laser direct writing |
UV-Curable Adhesives | Fast cure, good adhesion to metals and plastics |
UV Inks and Coatings | Suitable for offset, screen, and flexo systems requiring high reactivity and low yellowing |
Advanced Packaging | Encapsulation of semiconductors and PCB assembly |
Holography and Waveguides | Precision imaging and data storage applications |
SINOCURE® BCIM offers a reliable and cost-effective alternative to imported HABI-type photoinitiators. With consistent quality, stable manufacturing, and a global supply chain, we ensure that your production lines run without interruption.
BCIM is typically used at 0.1 – 5.0 wt% based on total formulation solids. For optimal performance, we recommend combining with:
Co-initiators: LC Verdigris (LCV), thiols (e.g., dodecanethiol), or tertiary amines
Photosensitizers: EMK, ITX, or visible light-absorbing dyes when longer wavelength exposure is required
Monomer blends: multifunctional acrylates such as TMPTA, DPHA, PETA for high crosslinking density
Feature | Benefit |
High thermal stability | Suitable for wider processing windows |
Excellent solubility | Easy to incorporate into resins, reactive monomers, and solvents |
Reversible radical generation | Low migration and extractables |
Good sensitivity | Efficient cure in dry film systems and photoresists |
Consistent batch quality | Reliable production output |
SINOCURE® BCIM is available in:
Carton boxes: 20 kg per carton
Fiber drums: 25 kg per drum
Other pack sizes available upon request
Custom packaging can be arranged for high-volume contracts.
Store in a dry, clean, well‑ventilated warehouse
Protect from direct sunlight and heat sources
Keep containers tightly sealed after use
Avoid prolonged exposure to elevated temperatures
Shelf life: 12 months when stored under recommended conditions.
If stored longer, retest before use to ensure performance.
Sinocure Chemical Group is a trusted manufacturer and supplier of specialty photoinitiators, UV monomers, oligomers, and additives. We support research and development teams with comprehensive technical data, sample service, and custom specifications.
Verified manufacturing – Strict quality control from raw material to finished product
Global supply reach – Reliable delivery to key international markets
Customer-first service – Technical support and responsive communication
Ready to test SINOCURE® BCIM in your formulation? We offer free samples for qualified projects and can assist with formulation optimization.
Email: info@sinocurechem.com
Website: https://www.sinocurechem.com
