Abstract: Photocurable liquid coating compositions adapted to provide primary coatings for optical glass fibers are disclosed. These compositions comprise an acrylate-terminated polyurethane, an acrylate of an unsubstituted or C.sub.1 -C.sub.10 alkyl substituted phenol that is alkoxylated with a C.sub.2 -C.sub.4 alkylene oxide and at least one alkylacrylate having a T.sub.g below about -45.degree. C. Films produced from these ultraviolet light curable compositions are flexible and possess good water resistance and good wet adhesion.

Abstract: Photocurable liquid coating compositions adapted to provide primary coatings for optical glass fibers are disclosed. These compositions comprise polycarbonate-based acrylate-terminated polyurethane, an acrylate of an unsubstituted or C.sub.1 -C.sub.10 alkyl substituted phenol that is alkoxylated with a C.sub.2 -C.sub.4 alkylene oxide and at least one alkylacrylate having a T.sub.g below about -45.degree. C. Films produced from these ultraviolet light curable compositions are flexible and possess good water resistance and good wet adhesion.

Abstract: A light-curable ethylenically unsaturated liquid coating composition which cures to provide low modulus coatings adapted for the primary or single coat coating of optical glass fiber and having improved adhesion is disclosed. This composition comprises:(1) an acrylate-terminated polyurethane oligomer;(2) a monoethylenically unsaturated liquid having a glass transition temperature, measured on a homopolymer thereof, below about 0.degree. C. and which reduces the glass transition temperature of the coating; and(3) a silsesquioxane oligomer polyacrylate which is the condensation reaction product of about two moles of hydroxyalkyl acrylate in which the alkyl group contains from 2 to 4 carbon atoms, with about one mole of a silsesquioxane polysilanol, the proportion of the silsesquioxane oligomer polyacrylate is in the range of from about 2% to about 60% of the weight of the coating composition.