Abstract: A novel phosphorus fire retardant, 1,2,3-tri(5,5-dimethyl-1,3, -dioxaphosphorinanyl-2-oxy)benzene (FR), was synthesized from 1,2,3-tri(hydroxy)benzene, neopentyl glycol, and phosphorus oxychloride, and was employed in epoxy resin system. The flame retarding effect on limited oxygen index (LOI) and UL-94 was studied. It showed that FR was effective on the flame retardancy of epoxy resin at a content of 20 %, UL94 V-0 rating and an LOI of 27.8 % were reached. The cone experiment showed that the av-HRR and av-SEA of the FR-containing epoxy resin were 77.0 % and 82.8 % lower than neat resin, respectively. SEM observation revealed that a continuous, dense, strong, and closed charred layer was formed.

Key words: 1, 2, 3-tri(5, 5-dimethyl-1, 3 -dioxaphosphorinanyl-2-oxy)benzene, phosphorus fire retardant, fire retardancy, epoxy resin