The present invention relates to new reactive systems comprising organic polyisocyanates, organic polyepoxides, polymer modifiers, special catalysts and optionally other auxiliary agents and additives.
Reactive systems based on epoxide/isocyanate (EPIC) components are described, for example, in DE 36 44 382.
EPIC resins have good processing and curing properties and when cured give rise to articles having good mechanical strength, chemical resistance and high glass transition temperatures. However, the products are relatively brittle. The same applies to epoxide resins and duroplasts, in general.
It has long been the wish of users of such products to have available duroplastic synthetic resins which combine high rigidity with chemical resistance, heat resistance, improved toughness and ductility.
It was, therefore, an objective of this invention to develop EPIC resins which when cured give rise to articles with improved toughness without loss of rigidity and heat resistance. The present invention provided EPIC resins which meet this objective by employing polymer modifiers. It is known that modifiers are used as polymer blending partners for thermoplastic synthetic resin blends (e.g. on the basis of polyvinyl chloride (PVC). It was, however, surprising that polymer modifiers of the type of graft rubbers achieve the objective of this invention.