Abstract: Radiation-curable coating compositions particularly adapted for the single coat coating of optical fibers are disclosed. These comprise (1) from 65% to 85% of a diethylenic-terminated polyurethane, which may contain urea groups, the polyurethane being based on a diisocyanate having an average molecular weight of from 400 to 5000; and (2) from 5% to 25% of an ether of a C.sub.2 -C.sub.4 alkylene glycol monoester of a monoethylenically unsaturated monocarboxylic acid, the ether being selected from the group consisting of ethoxyethyl, dicyclopentenyl, phenyl, and mixtures thereof. Ethoxyethoxyethyl acrylate is particularly preferred. A triacrylate ester, such as trimethylol propane triacrylate, is also desirably present.

Abstract: Freshly drawn optical glass fiber is protected by coating it with an ultraviolet-initiated, cationically curable liquid coating composition comprising a cationically curable polyepoxide, a polysiloxane carrying a plurality of hydroxyalkyl groups, and a photoinitiator and/or photosensitizer for an ultraviolet-activated cationic cure. The coatings are of low modulus and retain a low modulus at temperatures as low as -60.degree. C.

Abstract: A liquid ultraviolet-curable coating composition contains at least 45% up to 95% by weight of acrylated polyurethane-based oligomer comprising at least 10%, based on the total weight of polymerizable material, of an acrylated polyurethane-based ultraviolet-curable oligomer in which the oligomer is the reaction product of an organic diisocyanate with an polyepichlorohydrin polyether diol having a number average molecular weight of from about 1,000 to about 15,000, this reaction product being capped at each end thereof with a monohydric acrylate. At least about 5% up to 55% of the composition is a liquid acrylate-functional compound providing the coating composition with coating viscosity.

Abstract: Thermally curable wet-impregnated rovings in which the fibers of the roving are impregnated with liquid polyepoxides lacking polymerizable unsaturation and having dispersed therein a latent heat-activatable epoxy curing catalyst, such as dicyandiamide. The polyepoxide dispersion has a room temperature viscosity of from 2000 to 5000 centipoises and a tack of less than about 6 on a Thwing-Albert inkometer. The rovings are produced without organic solvent using an elevated temperature which is insufficient to activate the curing catalyst and which lowers the viscosity to enable uniform impregnation in the absence of excess impregnant. The wet rovings can be stored without running in a supply package which may be cop wound, and running is also resisted in a void-free wet fiber composite so that the wet composite can be wrapped and then heated to cure the same.

Abstract: Buffer-coated and overcoated optical glass fiber is disclosed in which the topcoat has the high strength and high tensile modulus combined with good elongation and water resistance associated with extruded jacket coatings, but which is applied by ordinary coating procedures and cured by exposure to ultraviolet radiation. The coating compositions which enable this to be achieved comprise 30% to about 80% of linear diacrylate-functional polyurethanes which are the linear polyurethane reaction product of polycarbonate diol with organic diisocyanate in molar proportions providing an average of at least about 2 urethane linkages per molecule, these linear polyurethanes being end-capped with acrylate groups, and these polyurethanes being used in combination with at least 15% of liquid monoethylenically unsaturated monomer having a glass transition temperature above about 55.degree. C.

Abstract: Radiation-curable coating compositions adapted for application to buffer-coated optical fibers are disclosed. These are intended to apply an adherent topcoat having greater toughness and greater hardness than the buffer coating. The new compositions comprise: (1) from 25% to 70% of diethylenic-terminated polyurethane, which may include urea linkages, the polyurethane being based on a diisocyanate having an average molecular weight of from 400 to 5000; (2) from 5% to 40% of a diethylenically unsaturated ester of a diglycidyl ether of a bisphenol, said ether having a molecular weight up to about 1000; and (3) from 5% to 30% of liquid radiation-curable monoethylenically unsaturated monomer having a T.sub.g above about 55.degree. C., especially N-vinyl pyrrolidone. Ultraviolet cures using acrylates as the ethylenic group are preferred.

Abstract: Radiation-curable coating compositions particularly adapted to reduce the adhesion of the radiation-cured coatings to glass optical fibers (and thereby enhance strippability) are disclosed. These comprise a radiation-curable polyethylenic organic compound and from about 2% to about 20% of the coating composition of an organic polysiloxane carrying a plurality of hydroxy-terminated groups which are joined to some of the silicon atoms in the polysiloxane chain by a carbon-to-silicon bond. The polysiloxane reduces the adhesion of the radiation-cured coating to the glass surface of the fiber. Ultraviolet cures using acrylates as the ethylenic group are preferred.