Epoxy resin adhesives are composed of an epoxy resin and a hardener. In order to generate a high-performance adhesive, ten or more additives are included in the formulation; these additives must be carefully adjusted to each other because of their mutual interactions.
The primary epoxy resins used are bis-phenol-A diglycidyl ether (BDGE) or bis — phenol-F diglycidyl ether. Reactive low-viscosity diluents (e. g. hexanediol diglycidyl
Figure 5.17 Viscosity of one-part and two-part toughened epoxy adhesives depending on time and temperature. |
ether) are frequently added to regulate the viscosity, to obtain higher filling rates, and to improve the wetting properties of the substrate.