Abstract
Acrylate esters having different molecular weight of the polyethylene glycol units were blended with diallyl phthalate (DAP) resin to improve the fracture toughness and the adhesive properties. These blends were cured with dicumyl peroxide. By modification with acrylate esters, the fracture toughness, the T-peel adhesive strength and the lap shear adhesive strength to copper were improved. In particular, the fracture toughness and the adhesive strength were greatly improved when the DAP resin was modified with the acrylate esters having the large molecular weight of a polyethylene glycol unit, or with blending ratio of acrylate acid ester was larger. It is thought that the reason for this result is that flexibility was given by the introduction of the polyethylene glycol unit; as a result, an internal stress of the adhesive layer occurring in a curing process was relaxed. The DAP resin modified with acrylate esters showed a sequential-IPN structure when the acrylate ester having the small molecular weight of the polyethylene glycol unit was blended and blending ratio of acrylate esters having the large molecular weight was small. While, the DAP resin modified with acrylate esters showed a phase-separated IPN structure when it was blended 20wt% or more acrylate ester having the large molecular weight of the polyethylene glycol unit.
