When choosing adhesives, manufacturers can choose cyanoacrylates, which provide a one-part, room-temperature cure. However, the adhesives can cause blooming, vapor deposits that import a frosty look. Also, cyanoacrylates are targeted for thin gap bonds.
Then there's UV-light-cure adhesives. These instantly curing adhesives experience no blooming, and can be used for thicker cure and bond lines. The catch? You've got to get the UV curing light into the bond line.
Enter Loctite Corp.'s (Rocky Hill, CT) FLASHCURETM adhesives, which combine the two chemistries' advantages. Loctite says the products offer the user instant fixtures and tack-free surfaces in less than 5 sec when exposed to low-, medium-, or high-intensity light. Plus, the adhesives cure tack-free without the use of solvent-borne accelerators, Loctite adds.
The ISO-10993/USP Class VI-compliant adhesives are available in two versions: 4302, a low-viscosity adhesive for use with close-fitting parts, and 4303, a medium-viscosity adhesive that fills larger gaps. A secondary moisture cure mechanism, allows the adhesives to cure completely in shadowed areas where light cannot reach.
Says Jerry Perkins, director of general industrial OE marketing for Loctite. "The FLASHCURE adhesives are great for high-volume manufacturing because of the speed of cure, and for use in traditionally difficult applications for UV adhesives because of the shadow areas. Plus, they don't bloom."