CURE BEHAVIOR OF SILICONE-EPOXIES AND URETHANE MODIFIED ACRYLATES IN INTERPENETRATING POLYMER NETWORKS

In an attempt to improve the toughness and flexibility of poly (epoxy- urethane-acrylic), interpenetrating polymer network (IPN) coatings con ventional bisphenol A type epoxy was replaced with silicone containing epoxy. By comparing silicone epoxy containing samples with bisphenol. A controls, the effect of siloxane modification on. the properties of the materials thus formed were tested. The coatings were formulated t o typical automotive primer conditions (in the absence of any pigments ) and tested for solvent resistance, lap shear strength, impact resist ance, and thermal stability. The formation of IPNs was established by changes in the thermal behavior of the coatings as well as by the syne rgistic effects no ted in, the physical and mechanical properties achi eved in the formulated coatings. In formation of the silicone modified IPNs, however, it was noted thar cure response was diminished versus control. Therefore, we undertook a cure study to determine the effects of catalysts and trifunctional acrylates on the resultant properties in the IPN coatings, This paper describes the chemistries and formulat ions utilized in attaining the aforementioned properties.