Arylalkylsilyls used as flame retardant additives

1. A flame retarded resin composition comprising at least one resin selected from the group consisting of polycarbonate, polyester and mixtures thereof, and a flame retarding effective amount of at least one nonhalogenated arylalkylsilyl flame retardant represented by the formula

wherein R 1 , R 3 , R 5 and R 6 each independently is aryl or substituted aryl; R 2 and R 4 each independently is a lower alkyl; X is a bridging group derived from a diol possessing an arylene moiety; and, n has a value of up to about 20; the flame retardant resin composition being substantially free of haloorganic flame retardant and phosphate flame retardant.

2. The flame retarded resin composition of claim 1 wherein the polycarbonate resin is an aromatic polycarbonate and the polyester resin is an aromatic polyester.

3. The flame retarded resin composition of claim 1 further comprising at least one other molding grade thermoplastic resin.

4. The flame retarded resin composition of claim 3 wherein the other molding grade thermoplastic resin is selected from the group consisting of polystyrene, acrylonitrile-butadiene-styrene, high impact polystyrene, polyamides, polyethylene, polypropylene, polysulfone, polyvinyl acetate, ethylene-vinyl acetate copolymers, poly(methyl methacrylate), polyethylene oxide, cellulose acetate, cellulose nitrate and mixtures thereof.

5. The flame retarded resin composition of claim 2 further comprising at least one other molding grade thermoplastic resin.

6. The flame retarded resin composition of claim 5 wherein the other molding grade thermoplastic resin is selected from the group consisting of polystyrene, acrylonitrile-butadiene-styrene, high impact polystyrene, polyamides, polyethylene, polypropylene, polysulfone, polyvinyl acetate, ethylene-vinyl acetate copolymers, poly(methyl methacrylate), polyethylene oxide, cellulose acetate, cellulose nitrate and mixtures thereof.

7. The flame retarded resin composition of claim 1 wherein the polycarbonate resin is present at a level of from about 70 to about 100 weight %.

8. The flame retarded resin composition of claim 1 wherein the polyester resin is present at a level of from about 70 to about 100 weight %.

9. The flame retarded resin composition of claim 1 wherein the polycarbonate resin is present at a level of from about 50 to about 100 weight %.

10. The flame retarded resin composition of claim 1 wherein the polyester resin is present at a level of from about 50 to about 100 weight %.

11. The flame retarded resin composition of claim 3 wherein the other thermoplastic resin is present at a level up to about 50 weight %.

12. The flame retarded resin composition of claim 3 wherein the other thermoplastic resin is present at a level of up to about 30 weight %.

13. The flame retarded composition of claim 1 wherein R 1 , R 3 , R 5 and R 6 each independently is aryl or substituted aryl of from 6 to about 22 carbon atoms, R 2 and R 4 each independently is a lower alkyl of from 1 to about 4 carbon atoms, and n has a value of up to 5.

14. The flame retarded composition of claim 1 wherein R 2 and R 4 each is a methyl group.

15. The flame retarded composition of claim 1 wherein bridging group x is represented by one of the following structures:

16. The flame retarded composition of claim 1 wherein n is 1 or 2.

17. The flame retarded composition of claim 1 wherein the arylalkysilyl flame retardant is present at a level of from 1 to about 30 weight %.

18. The flame retarded composition of claim 2 wherein R 1 , R 3 , R 5 and R 6 each independently is aryl or substituted aryl of from 6 to about 22 carbon atoms, R 2 and R 4 each independently is a lower alkyl of from 1 to about 4 carbon atoms, and n has a value of up to 5.

19. The flame retarded composition of claim 2 wherein R 2 and R 4 each is a methyl group.

20. The flame retarded composition of claim 2 wherein bridging group x is represented by one of the following structures:

21. The flame retarded composition of claim 2 wherein n is 1 or 2.

22. The flame retarded composition of claim 2 wherein the arylalkysilyl flame retardant is present at a level of from 1 to about 30 weight %.

23. The flame retarded composition of claim 3 wherein R 1 , R 3 , R 5 and R 6 each independently is aryl or substituted aryl of from 6 to about 22 carbon atoms, R 2 and R 4 each independently is a lower alkyl of from 1 to about 4 carbon atoms, and n has a value of up to 5.

24. The flame retarded composition of claim 3 wherein R 2 and R 4 each is a methyl group.

25. The flame retarded composition of claim 3 wherein bridging group X is represented by one of the following structures:

26. The flame retarded composition of claim 3 wherein n is 1 or 2.

27. The flame retarded composition of claim 3 wherein the arylalkysilyl flame retardant is present at a level of from 1 to about 30 weight %.

28. The flame retarded composition of claim 5 wherein R 1 , R 3 , R 5 and R 6 each independently is aryl or substituted aryl of from 6 to about 22 carbon atoms, R 2 and R 4 each independently is a lower alkyl of from 1 to about 4 carbon atoms, and n has a value of up to 5.

29. The flame retarded composition of claim 5 wherein R 2 and R 4 each is a methyl group.

30. The flame retarded composition of claim 5 wherein bridging group x is represented by one of the following structures:

31. The flame retarded composition of claim 5 wherein n is 1 or 2.

32. The flame retarded composition of claim 5 wherein the arylalkysilyl flame retardant is present at a level of from 1 to about 30 weight %.

33. A method for making arylalkylsilyl flame retardant of claim 1 having a high weight ratio of dimer to oligomer which comprises reacting a molar excess of an alkyltrichlorosilane with a diphenol to obtain a diphenyl bis(dichloroalkylsilane), removing unreacted alkyltrichlorosilane by distillation, reacting the diphenyl bis(dichloroalkylsilane) from which unreacted aklyltrichlorosilane has been removed with a molar excess of the same or different phenol to provide arylalkylsilyl flame retardant and removing unreacted phenol from the arylalkysilyl flame retardant by distillation.