DOPO-derived flame retardant and epoxy resin composition

1. A flame retardant epoxy composition comprising:

(i) an epoxy resin;

(ii) a compound having the following structure:

wherein A is a direct bond, C 6 -C 12 aryl, C 3 -C 12 cycloalkyl, or a C 3 -C 12 cycloalkenyl, wherein said cycloalkyl or cycloalkenyl may be optionally substituted by a C 1 -C 6 alkyl;

each R 1 , R 2 , R 3 and R 4 are independently hydrogen, C 1 -C 15 alkyl, C 6 -C 12 aryl, C 7 -C 15 aralkyl or C 7 -C 15 alkaryl; or R 1 and R 2 or R 3 and R 4 taken together can form a saturated or unsaturated cyclic ring, wherein said saturated or unsaturated cyclic ring may be optional substituted by a C 1 -C 6 alkyl;

each m is independently 1, 2, 3 or 4

each R 5 and R 6 are independently hydrogen or a C 1 -C 6 alkyl;

each n is independently 0, 1, 2, 3, 4 or 5;

with the proviso that when A is aryl or a direct bond, n can not be 0.

2. The composition of claim 1 , wherein both n subscripts are 1 or 2 and A is a direct bond.

3. The composition of claim 1 , wherein both n subscripts are 1 and A is a C 6 -C 12 aryl.

4. The compound of claim 2 , wherein R 1 , R 2 , R 3 and R 4 are independently hydrogen or a C 1 -C 6 alkyl.

5. The composition of claim 1 wherein the compound of Formula I is 6H-Dibenz[c,e][1,2]oxaphosphorin, 6,6′-(1,4-ethanediyl)bis-, 6,6′-dioxide; 6H-Dibenz[c,e][1,2]oxaphosphorin, 6,6′-(1,4-butanediyl)bis-,6,6′-dioxide; or 6H-Dibenz[c,e][1,2]oxaphosphorin, 6,6′-(p-xylenediyl)bis-,6,6′-dioxide.

6. The composition of claim 5 , wherein the compound of Formula I is 6H-Dibenz[c,e][1,2]oxaphosphorin, 6,6′-(1,4-ethanediyl)bis-, 6,6′-dioxide.

7. The composition of claim 1 , wherein said epoxy compound is an polyphenol epoxy resin derived from bisphenol A, tetramethylbisphenol A, bisphenol F, bisphenol S, tetrakisphenylolethane, polybenzoxazine, resorcinol, 4,4′-biphenyl or dihydroxynaphthylene; novolac epoxy resin derived from phenol/formaldehyde novolac, cresol/formaldehyde novolac, bisphenol A novolac, biphenyl-, toluene-, xylene-, or mesitylene-modified phenol/formaldehyde novolac or aminotriazine novolac; heterocyclic epoxy resins derived from p-amino phenol or cyanuric acid; and aliphatic epoxy resins derived from 1,4-butanediol, glycerol or dicyclopentadiene; or mixtures thereof.

8. A cured flame retardant epoxyresin comprising reacting the composition of claim 6 with a curing or polymer initiation agent.

9. The resin of claim 8 , wherein the organic phosphorous content of the composition is about 0.5 wt % to about 10 wt %, based on the total weight of the resin.

10. The composition of claim 8 , further comprising a melamine polyphosphate.

11. The composition of claim 8 , further comprising silica.

12. The composition of claim 8 , wherein the d 50 particle of the compound of Formula I is less than about 15 microns.

13. A prepreg comprising an organic or inorganic reinforcing material and the flame retardant epoxy composition of claim 6 .

14. A laminate formed from the prepreg of claim 13 .

15. A printed wiring board formed from the laminate of claim 14 .