SYNTHESIS AND PROPERTIES OF EPOXY-RESINS CONTAINING DIBENZ[C,E][1,2]OXAPHOSPHORIN-6-YL)1,4-BENZENEDIOL

2-(6-Oxid-6H-dibenz[c,e][1,2]oxa-phosphorin-6-yl) 1,4-benzenediol (ODO PB) was prepared by the addition reaction between 9,10-dihydro-9-oxa-1 0-phosphaphenanthrene-10-oxide (DOPO) and p-benzoquinone while DOPO wa s synthesized through multistep reaction from o-phenylphenol and phosp horus trichloride. The compound (ODOPB) was used as a reactive flame-r etardant in o-cresol formaldehyde novolac epoxy resin (CNE) for electr onic application. Owing to the rigid structure of ODOPB and pendant P group, the resultant phosphorus containing epoxy resin exhibited bette r flame retardance, higher glass transition temperature and thermal st ability than the regular bromine-containing flame-retardant epoxy resi n. UL 94-VO rating could be achieved with a phosphorus content of as l ow as 1.1% (comparable to a bromine content of 6%) in the cured resin and no fume and toxic gas emission were observed. (C) 1998 Published b y Elsevier Science Ltd. All rights reserved.