| abstract |
The present invention relates to unsaturated polyester resin or vinyl ester resin compositions; that are curable with a peroxide component; and that, comprise a salt and/or a base, a polymer containing reactive unsaturations, optionally a reactive diluent, and a dioxo-component; which compositions are essentially free of cobalt; and contain either as the salt an organic or inorganic salt of which the cation has a redox potential of the metal of at most -1 V, or is an ammonium ion; and/or as the base either an inorganic base of which the cation has a redox potential of the metal of at most -1 V, or a nitrogen containing organic compound; and in which the dioxo-component consists of one or more dioxo-compounds having a calculated reduction energy (CRE), being the energy difference in kcal/mole between the lowest energy conformations of the radical anion and the corresponding neutral molecule as calculated by means of the Turbomole Version 5 program, in the range of from -5 to -30 kcal/mole. These resin compositions show a reduced gel-time drift tendency. Moreover, it has been found that gel-time of these resin compositions can be easily and favorably adjusted by varying the amount of base. The present invention further also relates to objects and structural parts prepared from such unsaturated polyester or vinyl ester resin compositions by curing with a peroxide. The present invention finally also relates to methods of peroxide curing of unsaturated polyester resin or vinyl ester resin compositions. |