Polymer Bulletin 47, 437-444 (2002) Polymer Bulletin  Springer-Verlag 2002 Preparation of novel UV-curable methacrylated urethane resins from a modified epoxy resin and isocyanatoethylmethacrylate (IEM) Tülay Y lmaz nan 1,2 , Ekrem Ekinci 1 , Abdülkadir Kuyulu 1,3 , Attila Güngör 1,4 1 Marmara Research Center, Material and Chemical Technologies Research Institute, P.O. Box 21, 41470, Gebze-Kocaeli, Turkey 2 Department of Chemical Engineering, Istanbul Technical University, Maslak- stanbul, Turkey 3 Department of Chemical Engineering, Y ld z Technical University, 34210, Esenler- stanbul, Turkey 4 Faculty of Art&Sci., Department of Chemistry, Marmara University, Göztepe- stanbul, Turkey Received: 26 June 2001/Revised version: 5 April 2001/Accepted: 5 April 2001 Summary New UV curable methacrylated urethanes (PAPHEN-XIEM) were synthesized by substituting X percent (e.g., 10, 20, 30 %) of the total OH content of the PAPHEN-301 (Scheme 1) with isocyanatoethyl methacrylate (IEM). These resins were used alone (neat resin formulation) or as a mixture of 5, 10 and 13 % (w/w) respectively with methacrylated urethane prepolymer (PTHFUMA) in UV systems. For neat resin formulations, tensile strength and modulus values were observed to be inversely proportional with the modification degree of PAPHEN-301 as opposed to what is normally expected. This may be explained as a result of screening effect of increasing unsaturation. The water absorption capacities for neat resins and PTHFUMA-included formulations were decreased as the modification degree increased due to the replacement of hydrophilic OH groups of PAPHEN-301 by the hydrophobic methacrylate groups. TGA thermograms of neat resin formulation show that, initial weight loss temperatures are lower; possibly owing to the higher methacrylate content in the formulations. Introduction Radiation curable coating applications have been increasing due to the advantages such as lower energy consumption, less environmental pollution and very rapid curing (1-3). In general, UV curable coating formulations are consisted of primarily three major components; namely, a reactive oligomer, end-capped with a functional group such as acrylic or methacrylic, a mono or polyfunctional reactive diluents, and a photoinitiator. Nonreactive additives such as pigments, adhesion promoters, surface active agents, may be used in formulations depending on the specific application. However, reactive oligomers, which govern the mechanical properties of the UV-cured films, are the major ingredients in these formulations (1-7). In this study, we used N-vinyl-2-pyrrolidone (NVP) as the reactive diluent (NVP) due to its powerful solvating effect, diethylene glycol dimethacrylate (DEGDA) as crosslinking agent and isobutyl benzoin ether (IBuBE) and dibutyltin dilaurate (DBTDL) as photoinitiator and catalyst, respectively. PAPHEN-301 (Scheme 1) is a tough, ductile epoxy based thermoplastic resin with good cohesive strength and good impact resistance. Its ether linkage and pendant hydroxyl groups promote wetting and bonding to polar substrates and fillers. It is compatible with many polymers and is an efficient flexibilizer for cross-linked formulations. It improves the performance of metal primers and coatings for metal, wood, and flexible substrates. It imparts outstanding properties in magnetic tape, adhesive, molding and extrusion applications (8).