URETHANE-ACRYLATE COMPOSITIONS CURED BY UV-RADIATION AS INTERMEDIATE PROTECTIVE COVERS OF OPTICAL FIBERS

The present paper deals with studies concerned with an optimization of the synthesis of urethane-acrylic UV-cured resins intended for applic ation as protective coatings for optical fibers. Oligoetherdi- and tri ols, toluylene diisocyanate and isophorone diisocyanate, as well as hy droxyethyl methacrylate and hydroxypropyl methacrylate were used for s ynthesis. Active diluents butyl acrylate, 2-ethylhexyl acrylate, 1,4-b utanediol diacrylate or their mixtures, and 2,2-dimethoxy-2-phenylacet ophenone as a photoinitiator were added to the urethane-acrylic dimers comprising polymerization-active double bonds. The compositions were characterized by the determination of density, viscosity, refractive i ndex, gel content, glass transition temperature, Shore hardness, Young 's modulus, breaking stress, relative elongation at break, thermal res istance and water vapour diffusion coefficient before and after curing . The utility of these compositions for protective intermediate coatin gs of optical fibers was checked and confirmed under manufacturing con ditions.