Polyacrylated oligomers in ultraviolet curable optical fiber coatings

Abstract

An ultraviolet curing liquid coating composition is disclosed which, when cured with ultraviolet light in the presence of an appropriate photoinitiator, provides buffer coatings for optical glass fiber having adequate strength at room or expected elevated temperature and stability at such elevated temperature, a high index of refraction above 1.48, and a low tensile modulus which remains low to resist microbending difficulties down to around -60.degree. C. This coating composition consists essentially of a linear polyacrylate-terminated polyurethane or polyurea oligomer having a room temperature tensile modulus of at least 100 psi., and a tensile modulus at -60.degree. C. which is less than 175,000 psi., when capped with 2-hydroxyethyl acrylate and cured with ultraviolet light, in admixture with a liquid acrylate-functional material which does not increase the low temperature hardness and which provides the liquidity needed for coating application. The oligomer is instead capped with a monohydric polyacrylate to provide improved cure speed without eliminating resistance to low temperature microbending.

Dependencies are inferred from the claim text.