Breakthrough in Low-Migration UV Photoinitiator | Copolymerizable Benzophenone Photoinitiator Monomer (CAS 1137971-16-4) Solves Migration, Odor and Precipitation Pain Points in UV Curing Industry

              Introduction

With increasingly stringent environmental regulations for food packaging, medical consumables, high-end electronic inks and optical coatings, traditional small-molecule benzophenone photoinitiators have long restricted the upgrading of high-end UV formulations due to drawbacks such as easy migration after curing, high extractables and residual odor in films. The new-generation copolymerizable benzophenone photoinitiator monomer (CAS 1137971-16-4) integrates benzophenone photosensitive groups and polymerizable acrylic double bonds in one molecule. It realizes dual functions of photoinitiation + crosslinking monomer, fundamentally inhibiting photoinitiator migration at the molecular structure level. It provides a brand-new solution for low-VOC, low-extractable and high-safety UV curing systems, helping coating, ink and adhesive manufacturers break the access threshold of high-end applications.

Technical Principle

CAS 1137971-16-4 is a reactive benzophenone photoinitiator monomer. Its molecule contains both benzophenone photosensitive moiety and polymerizable acrylic double bond, as well as flexible diether ether segments. Under UV irradiation, the side-chain benzophenone group undergoes hydrogen abstraction reaction to rapidly generate free radicals and initiate resin polymerization and crosslinking. Meanwhile, the terminal acrylic double bond participates in free-radical copolymerization, and is anchored into the polymer cured network skeleton via covalent chemical bonds. Unlike conventional small-molecule photoinitiators which are only physically blended inside the coating film, after curing, the photosensitive groups are permanently locked in the polymer network and cannot migrate or precipitate freely. This greatly reduces extractables of cured films and eliminates migration contamination and residual odor caused by small-molecule photoinitiators. The flexible ether chain optimizes molecular polarity, significantly improving compatibility with mainstream UV resin systems, reducing risks of formula whitening, stratification and crystallization, and expanding formulation design flexibility.

Core Advantages

1.Ultra-low migration, low extractables and high safety Photosensitive groups are covalently bonded into cured films without free small molecule precipitation, greatly lowering extractables of cured materials. It can meet high-safety control scenarios including food-contact packaging, medical UV consumables and children’s products, and avoid unqualified inspection and product recall risks caused by excessive migration of small-molecule photoinitiators.

2.Dual function: photoinitiator & crosslinking monomer, simplifying formulation It possesses both photoinitiation activity and reactive crosslinking monomer properties, reducing the types of formulation additives, lowering difficulties in multi-component compounding and debugging, and simplifying supply chain management. Incorporated monomer participates in film formation, increases crosslink density of cured films and improves solvent resistance and boiling water resistance of coating layers.

3.Broad excellent compatibility with mainstream UV resins Built-in flexible diether ether segments offer good compatibility with epoxy acrylate, polyurethane acrylate, polyester acrylate, pure acrylate oligomers and various acrylic reactive diluents. It is not prone to precipitation, turbidity or whitening, suitable for 100% solid content solvent-free UV systems.

4.Stable curing efficiency with balanced comprehensive film properties It retains classic hydrogen-abstraction photoinitiation characteristics of benzophenone. When combined with amine co-initiators, UV curing reaction is stable and delivers good surface drying performance. Its addition will not significantly reduce hardness, adhesion and flexibility of cured films, balancing curing speed and mechanical properties of coatings.

5.Low odor & low VOC, complying with green environmental trend No free small molecule migration or volatilization after curing. The finished film odor is remarkably lower than conventional small-molecule benzophenone photoinitiators such as BP. It is suitable for low-odor environmentally friendly inks and optical protective films, complying with domestic and overseas VOC and REACH regulations.

Key Application Fields

✅ Food-contact UV inks and coatings: UV printing inks for flexible food packaging, paper-plastic UV varnish; meets low-migration requirements for food-contact materials and prevents migration contamination to contents.

✅ Medical-grade UV curing consumables: Medical UV adhesives, coatings for disposable devices, dental auxiliary UV resin; reduces extractables and satisfies biosafety control of medical materials.

✅ High-end electronic UV materials: FPC protective inks, optical adhesives, screen hard coating, UV encapsulation resin for electronic components; prevents haze and circuit contamination induced by small molecule migration.

✅ Environment-friendly wood/plastic UV coatings: Top UV finish for children’s toys and daily plastic products, solvent-free UV varnish for furniture; lowers finished product odor and upgrades product safety grade.

✅ UV adhesives: UV pressure-sensitive adhesives and structural adhesives for PET, PC and glass substrates; improves stability of adhesive layers and avoids debonding and yellowing caused by small molecule migration during long-term service.

Reference Physical & Chemical Index

Appearance: Colorless to pale yellow transparent liquid

Pt-Co Color: ≤50

Purity: ≥85%

Viscosity (25℃): 70~110mPa·s

Refractive index (20℃): 1.472~1.476

Acid Value (KOH mg/g): ≤0.3

Water Content: ≤0.1%

Inhibitor (MEHQ): 100~400 ppm

Recommendations for Use

This product is a hydrogen-abstraction copolymerizable photoinitiator monomer. It is recommended to use together with amine co-initiators to improve curing efficiency. It can partially replace traditional benzophenone photoinitiators. The dosage is generally 2%~8%, adjusted according to substrate, film thickness and UV lamp energy. It is suitable for solvent-free UV systems. Lab trials, pilot tests and compliance tests including migration and extraction tests are recommended in formulation development to evaluate long-term stability in end-use applications. Store in sealed and dark conditions away from heat sources. Avoid prolonged UV exposure to prevent premature monomer self-polymerization.

Industry Outlook

The global UV curing industry is shifting from basic performance to high safety, low extractables and green traceability. Downstream sectors including food, medical and optics are imposing stricter control on material extractables, while conventional small-molecule photoinitiators are hitting application bottlenecks. As a copolymerizable benzophenone photoinitiator monomer, CAS 1137971-16-4 adopts molecular anchoring design to fundamentally solve migration issues. It provides domestic UV material manufacturers with high-performance reactive photoinitiator alternatives, reduces reliance on imports of high-end UV raw materials, helps domestic UV ink, coating and new material enterprises seize high-end market segments, and empowers high-quality development of green photocuring industry.

Disclaimer: This document is marketing copy for product promotion. All data is for formulation R&D reference only. Please complete lab test, pilot test and compliance inspection before formal application. The final product performance shall be subject to batch COA.