How To by Hernon: Guide to Adhesive UV Curing
Guide to Adhesive UV Curing By Hernon Manufacturing
Adhesives and sealants are distributed and applied in an immature state. They do not reach their full potential until they undergo a process called polymerization. Commonly called curing or crosslinking, polymerization is a physical or chemical change that alters material properties. Typically, this change hardens the substance and in the case of adhesives, results in a tougher, more resilient material with greater bonding capabilities.
The UV polymerization method starts at adhesive factories and labs with the creation of materials that react to UV exposure. UV activated adhesives and sealants are formulated with an additional ingredient called photoinitiators. These photoinitiators are UV light sensitive and, when triggered, create a chain reaction that hardens the material.
An important and lesser known step in the UV curing process is aligning the frequency of the cure light with the activating frequency of the photoinitiators. This step is particularly important when using LED bulbs as LED light output is focused in a narrow band of the light spectrum. Hernon Manufacturing has an advantage here since they offer both adhesive manufacturing and UV curing equipment and can optimize the alignment of frequencies between cure lights and UV adhesives.
Many manufacturers choose UV curing due to the speed and control the process offers. Manufacturers are free to work uncured adhesives until their product is just right. Then, using UV light, the crosslinking is completed in just a few seconds. Moments later the cured products can be handled, packaged and shipped.
UV curing requires the adhesive material to be exposed and accessible to light. This limits the method for some situations but makes it an especially good choice when working with glass and other translucent materials. UV light can pass through such materials and cure areas which are hard to reach for chemical initiation or where heat curing may not be appropriate.
The image left is an example this. Artist Dianna Hanson created this sculpture “Northern Lights” using UV adhesive Ultrabond® 740 and a UV curing light.