Ultraviolet curable optical glass fiber coatings from acrylate terminated, end-branched polyurethane polyurea oligomers

摘要

Ultraviolet curing oligomers and liquid coating compositions based thereon are disclosed which cure with ultraviolet light in the presence of a photoinitiator. The coating compositions can provide either a single coating for optical glass fiber which resists microbending difficulties down to around -40 DEG C., or a topcoat for overcoating softer buffer coatings which resist microbending down to around -60 DEG C. The coating compositions consist essentially of the linear polyacrylate-terminated polyurethane polyurea oligomer in admixture with an ultraviolet curable liquid acrylate or polyacrylate to provide the liquidity needed for application and to adjust the hardness or softness of the cured coating for the selected single coat or topcoat utility. The oligomer contains a linear polyurethane core terminated by urea formation with a polyhydroxy-functional amine containing a single isocyanate-reactive amino hydrogen atom. The plurality of hydroxy-terminated branches provided by the amine are capped with an acrylate-functional compound, and the several acrylate-functional branches increase the toughness and the cure speed.