Facile preparation of a phosphinated bisphenol and its low water-absorption epoxy resins for halogen-free copper clad laminates

This study focuses on developing advanced epoxy resins with characteristic of low water absorption for halogen-free copper clad laminates (CCL). To achieve this goal, we prepared a bisphenol (1) with two phosphinate pendants via the nucleophilic addition of 9, 10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) with the 1,4-phenylene diamine-based benzoxazines (P-pd). A series of advanced epoxy resins (2) were prepared based on the advancement reaction of (1) and diglycidyl ether of bisphenol A (DGEBA). After curing of (2), the properties of the resulting thermosets such as glass transition temperature, coefficient of thermal expansion, thermal decomposition temperature, water absorption, and flame retardancy were evaluated. The structure-property relationship was also discussed. Experimental data show that the resulting epoxy thermosets display moderate-to-high Tg, good flame retardancy, high modulus, and very low water absorption.