Dual-Functional Copolymerizable Hydroxybenzophenone Monomer｜CAS 16613-04-0, A Low-Extraction Solution for Ophthalmics & High-End UV Curing

The global UV curing industry keeps evolving toward high safety, low migration and long weather resistance. High-end sectors including food-contact packaging, optical films, ophthalmic polymers and medical coatings impose increasingly stringent regulations on UV-curable materials. Traditional small-molecule benzophenone photoinitiators tend to migrate freely after curing, causing pungent odor, substrate contamination by leachables, excessive extractables and degraded weather resistance of films, which heavily restricts compliance of premium products.

CAS 16613-04-0, 2-(4-Benzoyl-3-hydroxyphenoxy) ethyl methacrylate, is an innovative ortho-hydroxybenzophenone copolymerizable functional monomer. Breaking the limitation of conventional reactive photoinitiators with only single curing initiation function, it integrates Type II hydrogen abstraction photoinitiation and long-term UV absorption within one molecule, delivering an integrated high-performance solution for high-safety free-radical UV curing systems.

Molecular Structure & Curing Mechanism

This product adopts rationally designed molecular architecture integrating three functional units: ortho-hydroxybenzophenone chromophore, flexible ether linker and polymerizable methacrylate double bond. The unique ortho-hydroxy structure on benzene ring endows outstanding UV capturing capability, while retaining the hydrogen abstraction photoactivity of benzophenone core.

Upon UV irradiation, benzophenone moiety rapidly undergoes hydrogen abstraction to generate free radicals and trigger crosslinking of acrylate resins. Meanwhile, the terminal methacrylate double bond participates in free radical polymerization and covalently anchors into the polymer network.

After curing, the photosensitive moiety is no longer present as free small molecules inside resin. It fundamentally suppresses migration, volatilization and blooming of photoinitiators, greatly reducing extractables in cured films and eliminating odor. The ortho-hydroxybenzophenone fragment continuously absorbs UV radiation to block polymer chain photodegradation, slowing film yellowing and chalking, achieving curing molding and anti-aging protection in one step. The flexible ether bridge improves molecular mobility and compatibility with various resins, reducing risks of whitening, delamination and precipitation in formulations.

Core Product Advantages

✅ Low migration & low extractables for strict safety compliance Photosensitive groups are covalently bonded into cured polymer network, fully avoiding contamination risks from small-molecule additive migration. Suitable for ophthalmic materials, medical substrates, food-contact packaging and other high-safety scenarios to pass extractable tests.

✅ Integrated dual function: photoinitiation + UV absorption Different from common reactive photoinitiating monomers, it owns both hydrogen-abstraction photoactivity and copolymerizable UV stabilization. It initiates resin crosslinking and endows cured films with long-term UV aging resistance simultaneously, simplifying formulation and minimizing compatibility risks brought by multiple additives.

✅ Excellent broad-spectrum formulation compatibility Flexible ether structure offers good miscibility with PU acrylate, epoxy acrylate, polyester acrylate, methacrylate resins and reactive diluents. Wide formulation window with low tendency toward delamination, crystallization or surface whitening.

✅ Superior optical stability Slight impact on transmittance after addition, ideal for transparent optical articles and delivers uniform flat films; outstanding performance in transparent optical systems with balanced surface curing.

✅ Hydrogen-abstraction photoinitiating system with controllable surface drying Synergize with tertiary amine co-initiators to boost surface curing efficiency and improve film tack-free performance. Copolymerizable tertiary amines are preferred to further cut migration risk of the whole formulation.

Basic Physicochemical Data

CAS No.: 16613-04-0 Chemical Name: 2-(4-Benzoyl-3-hydroxyphenoxy) ethyl 2-methylprop-2-enoate Molecular Formula: C₁₉H₁₈O₅ Molecular Weight: 326.34 Product Category: Copolymerizable benzophenone photoinitiating monomer / reactive UV absorber monomer

Typical Application Fields

✅ Ophthalmic polymer materials: soft contact lenses, intraocular lenses. Covalently copolymerized into substrate for UV blocking without small-molecule leaching to guarantee eye safety.

✅ Food-contact grade UV inks, overprint varnishes and flexible packaging laminating adhesives complying with food packaging safety regulations.

✅ Hardcoat on PET/PC optical films and optical resins to enhance weather resistance and retard yellowing.

✅ High-precision industrial photosensitive resins and premium 3D printing UV-curable consumables, balancing molding accuracy and long-term stability.

✅ UV coatings for medical substrates and surface curing coatings for cosmetic packaging.

✅ All free-radical UV curing systems with strict requirements on migration, extractables and UV aging resistance.

Formulation Guidelines

It is a hydrogen-abstraction reactive photoinitiating monomer with limited photoinitiation efficiency when used alone. Tertiary amine co-initiators are recommended in formulations; copolymerizable tertiary amines are preferred to further reduce overall migration risk of the system.

Recommended loading level: 2%~8%. Actual dosage needs lab trial verification combining coating thickness, UV wavelength & power, production line speed, to comprehensively evaluate curing speed, yellowing tendency, migration test results and mechanical & optical performance of cured films.

Storage & Safety Notes

Store sealed and protected from light in cool and dry warehouse, away from heat sources and strong oxidants. Prolonged light exposure will cause premature auto-polymerization and degrade product quality. Wear protective gloves and goggles during handling to prevent direct skin and eye contact. Refer to MSDS for full safety parameters.

Selection Comparison of Similar Series

CAS 16613-04-0: Methacrylate + ether linker + ortho-hydroxybenzophenone. Strongest dual photoinitiation & UV absorption, first choice for ophthalmic materials, relatively high molecular polarity, prominent anti-aging performance. CAS 2035-72-5: Methacrylate ester without long ether chain, higher molecular rigidity, suited for general optical resin systems. CAS 1137971-16-4: Acrylate with long ether chain, excellent flexibility, mainly for inks and flexible coatings for flexible packaging.