When exposed to UV or visible light, light-curing CAs instantly solidify to a tack-free solid without blooming or stress cracking. Because they require no solvent-borne accelerators to speed the cure process, light-cure CAs will not bloom or crack on sensitive substrates such as polycarbonate and acrylic. Any shadowed areas not exposed to light solidify using the CA's normal moisture cure process.
Low-odor/low-bloom formulations improve the aesthetics of final products by eliminating the white haze that can form on the assembly around the bond line. These adhesives are also free of the pungent odors that can be a safety concern for manufacturers.
Selecting the right instant adhesive
Selecting the proper instant adhesive for an application is critical to the success of the assembly in its end-use application. The selection process should start with answering a series of questions about the adhesive itself, the materials to be bonded, the assembly process, and the end-use environment.
- What performance attributes for the adhesive are critical to the end-use application? For example, surface-insensitive cyanoacrylates tolerate acidic or dry surfaces and low-humidity end-use environments. Thermally resistant formulations maintain bond strength at temperatures as high as 250F. Rubber-toughened formulations are crack- and impact-resistant for high-shock/vibration environments.
- What substrates will be bonded? CAs easily bond to a wide range of plastics, metals, and porous materials, and they can be used reliably on hard-to-bond plastics with the help of primers that improve bond strength.
- Will the adhesive fit easily into the assembly process? Consider the fixture and cure speed required for manufacturing and the dispensing equipment that will be used: manual or automated. By selecting the right equipment, manufacturers can enjoy a highly efficient assembly process, reduced waste, and consistent/reliable adhesive dispensing.
Ultimately, designers who know the basic performance profile for their adhesive -- fixture/cure time, health/safety concerns, bond strength requirements, abnormal stresses, and special end-use variables -- will be able to select the right instant adhesive for their needs.