Optimax® Cationic and Dual Cure UV Adhesives

Overview

Optimax® cationic and dual cure UV adhesives address one of the fundamental limitations of standard UV adhesive systems: the inability to cure in areas that UV light cannot reach. In complex assemblies — opaque substrates, deep cavities, overlapping components — standard free-radical UV chemistry leaves uncured adhesive, compromising bond integrity and reliability.

Cationic cure chemistry overcomes this through a secondary cure mechanism that continues after UV exposure has ended, a phenomenon known as dark cure. Dual cure systems combine UV initiation with heat or moisture as a secondary trigger, ensuring complete polymerisation throughout the bond line regardless of light accessibility. Grades such as Optimax® 6439 and 6440 are engineered for these demanding assemblies.

These adhesives are widely used in electronics, automotive, optical, and medical device manufacturing where complex geometries make complete UV access impossible.

Key Benefits

Complete curing in shadowed and opaque areas via dark cure
Low shrinkage and excellent dimensional stability
Excellent chemical resistance post-cure
Reduced oxygen inhibition compared to standard free-radical systems
Reliable mechanical performance in demanding industrial applications

Applications

Electronics and industrial assemblies with shielded bond lines
Opaque or thick components where UV cannot fully penetrate
Complex geometries in automotive interiors and lighting modules
Medical device assembly requiring full cure verification
Optical bonding applications with shadowed joints

Specification Guidance

Confirm the secondary cure conditions required — heat or moisture — and ensure these are achievable within your process. For heat-activated secondary cure, validate that the temperature required does not stress other assembly materials. Substrate compatibility testing is recommended before production deployment.