Abstract: A wet-on-dry process for coating a glass optical fiber with a radiation curable Primary Coating, comprising (a) operating a glass drawing tower to produce a glass optical fiber; (b) applying a radiation curable Primary Coating composition onto the surface of the optical fiber; (c) applying radiation to effect curing of said radiation curable Primary Coating composition; (d) applying a secondary coating to the Primary Coating; and (e) applying radiation to effect curing of said secondary coating. Also, a wet-on-wet process for coating a glass optical fiber with a radiation curable Primary Coating, comprising (a) operating a glass drawing tower to produce a glass optical fiber; (b) applying a radiation curable Primary Coating composition onto the surface of the optical fiber; (c) applying a secondary coating to the Primary Coating; and (d) applying radiation to effect curing of the Primary Coating and the secondary coating.

Abstract: Radiation curable coatings for use as a Primary Coating for optical fibers, optical fibers coated with said coatings and methods for the preparation of coated optical fibers. A radiation curable Primary Coating composition comprising: an oligomer; a diluent monomer; a photoinitiator; an antioxidant; and an adhesion promoter; wherein said oligomer is the reaction product of: a hydroxyethyl acrylate; an aromatic isocyanate; an aliphatic isocyanate; a polyol; a catalyst; and an inhibitor, wherein said catalyst is an organo bismuth catalyst; wherein said oligomer has a number average molecular weight of from at least about 4000 g/mol to less than or equal to about 15,000 g/mol; and wherein a cured film of said radiation curable coating composition has a peak tan delta Tg of from about ?25° C. to about ?45° C.; and a modulus of from about 0.50 MPa to about 1.2 MPa.

Abstract: Radiation curable coatings for use as a Primary Coating for optical fibers, optical fibers coated with said coatings and processes to coat the optical fiber are described and claimed. The radiation curable coating is a radiation curable Primary Coating composition comprising: an oligomer; a first diluent monomer; a second diluent monomer, a photoinitiator; an antioxidant; and an adhesion promoter; wherein said oligomer is the reaction product of: a hydroxyethyl acrylate; an aromatic isocyanate; an aliphatic isocyanate; a polyol; a catalyst; and an inhibitor, and wherein said oligomer has a number average molecular weight of from at least about 4000 g/mol to less than or equal to about 15,000 g/mol; wherein a cured film of said radiation curable primary coating composition has a peak tan delta Tg of from about ?25° C. to about ?45° C. and a modulus of from about 0.50 MPa to about 1.2 MPa.