Flame retardant polymer compositions

1. A flame retardant composition, comprising:

(a) a polyamide or polyester;

(b) a crosslinking agent,

(c) a flame retardant system comprising a metal phosphinate salt, a metal diphosphinate salt, or combination thereof; and

(d) a flame retardant system coagent,

wherein the flame retardant system and the flame retardant system coagent being different from one another;

wherein the crosslinking agent comprises two or more groups capable of forming free radicals under beta or gamma radiation; and further wherein the flame retardant system coagent is present in an amount of about 1 to about 50 wt % of the total weight of the composition and comprises a mineral flame retardant, a phosphorous flame retardant, boehmite, or a combination thereof.

2. The composition of claim 1 , wherein the metal phosphinate salt is of the formula (I) and the metal diphosphinate salt is of the formula (II)

wherein R 1 and R 2 are each independently hydrogen, a linear or branched C 1 -C 6 alkyl radical, or aryl radical; R 3 is a linear or branched C 1 -C 10 alkylene, arylene, alkylarylene, or arylalkylene radical; M is calcium, aluminum, magnesium, strontium, barium, or zinc; m is 2 or 3; n is 1 when x is 1 and m is 2; n is 3 when x is 2 and m is 3.

3. The composition of claim 1 , wherein the metal salt is an aluminum salt of dimethylphosphinic acid, an aluminum salt of methylethylphosphinic acid, or an aluminum salt of methylpropylphosphinic acid.

4. The composition of claim 1 , wherein the flame retardant system further comprises at least one nitrogen compound selected from the group consisting of condensation products of melamine and/or reaction products of condensation products of melamine with phosphoric acid, and/or mixtures thereof, melam, melem, melon, melamine, melamine cyanurate, melamine phosphate compounds, dimelamine phosphate, melamine pyrophosphate, melamine polyphosphate compounds, benzoguanamine compounds, terephthalic ester compounds of tris(hydroxyethyl) isocyanurate, allantoin compounds, glycoluril compounds, ammeline, ammelide, and combinations thereof.

5. The composition of claim 4 , wherein the nitrogen compound comprises a compound of the formula (III) to (VIII) or combinations comprising at least one of the foregoing nitrogen compounds

wherein R4, R5, and R6 are independently hydrogen, hydroxy, amino, or mono- or diC1-C8 alkyl amino; or C1-C8alkyl, C5-C16cycloalkyl, -alkylcycloalkyl, wherein each may be substituted by a hydroxyl or a C 1-C4hydroxyalkyl, C2-C8alkenyl, C1-C8alkoxy, -acyl, -acyloxy, C6-C2aryl, —OR12 and N(R12)R13 wherein R12 and R13 are each independently hydrogen, C1-C8alkyl, C5-Cl6cycloalkyl, or -alkylcycloalkyl; or are N-alicyclic or N-aromatic, where N-alicyclic denotes cyclic nitrogen containing compounds such as pyrrolidine, piperidine, imidazolidine, piperazine, and the like, and N-aromatic denotes nitrogen containing heteroaromatic ring compounds such as pyrrole, pyridine, imidazole, pyrazine, and the like; R7, R8, R9, R16 and R11 are independently hydrogen, C1-C8alkyl, C5-C16cycloalkyl or -alkyl(cycloalkyl), each may be substituted by a hydroxyl or a C1-C4hydroxyalkyl, C2-C8alkenyl, C1-C8alkoxy, -acyl, -acyloxy, C6-Cl2aryl, and —O—R12; X is phosphoric acid or pyrophosphoric acid; q is 1, 2, 3, or 4; and b is 1, 2, 3, or 4.

6. The composition of claim 4 , wherein the nitrogen compound is allantoin, benzoguanaine, glycoluril, melamine, melamine cyanurate, melamine phosphate, melamine pyrophosphate, melamine polyphosphate, or urea cyanurate.

7. The composition of claim 1 , wherein the polyamide is selected from the group consisting of nylon-6, nylon-6,6, nylon-4, nylon-4,6, nylon-12, nylon-6,10, nylon-6,9, nylon-6,12, nylon-9T, copolymer of nylon-6,6 and nylon-6, polyamide copolymers, polyamide blends, and combinations thereof.

8. The composition of claim 1 , wherein the polyamide or polyester is present in an amount of about 20 to about 96 wt % based on the total weight of the composition.

9. The composition of claim 1 , wherein the polyester is derived from an aliphatic diol and an aromatic dicarboxylic acid having repeating units of the following general formula:

wherein y is an integer of from 2 to 6. R is a C6-C20 aryl radical comprising a decarboxylated residue derived from an aromatic dicarboxylic acid, wherein the polyester optionally comprises units derived from aliphatic acid, aliphatic polyols, or a combination thereof in an amount of about 0.5 to about 5 wt % of the total weight of the composition.

10. The composition of claim 1 , wherein the polyester is poly(ethylene terephthalate), poly(1, 4-butylene terephthalate), poly(ethylene naphthanoate), poly(butylene naphthanoate), poly(propylene terephthalate), or a combination thereof.

11. The composition of claim 1 , wherein the crosslinking agent comprises two or more unsaturated groups.

12. The composition of claim 1 , wherein the crosslinking agent is a polyallylic compound or a polyol poly(meth)acrylate prepared from an aliphatic diol, triol, or tetraol containing 2-100 carbon atoms.

13. The composition of claim 1 , further comprising up to about 60 wt % of filler of the total weight of the composition.

14. The composition of claim 1 , wherein the filler is glass fiber, zinc borate, or a combination thereof.

15. The composition of claim 1 , further comprising up to about 20 wt % of a wear additive based on the total weight of the composition, wherein the wear additive is selected from the group consisting of polytetrafluoroethylene, molybdenum disulfide, graphite, aramide, carbon fiber, carbon powder, and combinations thereof.

16. The composition of claim 1 , wherein the composition is crosslinked with ionizing radiation to form a crosslinked composition.

17. The composition of claim 1 , wherein the composition after crosslinking exhibits at least one of the following:

(a) a Glow Wire Flammability Index as measured according to IEC-60695-2-1 of 960° C., or greater within the range of 0.8 to 3.2 millimeters thickness;

(b) a Glow Wire Ignition Temperature as measured according to IEC-60695-2-13 of 750° C., or greater within the range of 0.8 to 3.2 millimeters thickness; or

(c) a comparative tracking index measured according to International Electrotechnical Commission standard IEC-60112/3rd of class 1 or class 0.

18. The composition of claim 1 , wherein the flame retardant system coagent is boehmite.

19. The composition of claim 1 , wherein the mineral flame retardant is selected from a metal hydroxide, a hydroxycarbonate, a borate, an oxide mineral, or a combination thereof.

20. The composition of claim 1 , wherein the mineral flame retardant is selected from aluminum tri-hydroxide, aluminum oxide hydroxide, magnesium di-hydroxide, or a combination including at least one of the foregoing flame retardants.

21. The composition of claim 1 , wherein the phosphorus flame retardant is selected from a polyphosphonate, a polyphosphonate-polycarbonate copolymer, a phosphazene compound, an aryl phosphate, a sulphonate salt, or a combination thereof.

22. The composition of claim 21 , wherein the aryl phosphate is selected from resorcinol diphenyl phosphate, bisphenol A diphenyl phosphate, or a combination thereof.

23. The composition of claim 21 , wherein the phosphorus flame retardant comprises a polyphosphonate.

24. The composition of claim 23 , wherein the polyphosphonate comprises residues derived from diphenyl-methyl-phosphonate.

25. The composition of claim 24 , wherein the polyphosphonate comprises is a homopolymer comprising residues derived from diphenyl-methyl-phosphonate.

26. The composition of claim 21 , wherein the sulphonate salt is potassium diphenyl sulphone sulphonate, potassium perfluorobutane sulfonate, or a combination thereof.

27. The composition of claim 21 , wherein the phosphazene compound comprises a phenoxycyclophosphazene.

28. The composition of claim 1 , wherein the flame retardant composition produces a reduced level of acidic species when compared to a corresponding or reference composition in the absence of the flame retardant system coagent and reduction in the flame retardant system, produced under substantially identical compounding and molding conditions.

29. The composition of claim 1 , wherein the flame retardant composition substantially prevents or inhibits corrosion when compared to a corresponding or reference composition in the absence of the flame retardant system co-agent and reduction in the flame retardant system, produced under substantially identical compounding and molding conditions.

30. An article comprising the crosslinked composition of claim 16 .

31. A flame retardant composition, comprising:

(a) a polyamide or polyester;

(b) about 1 to about 20 wt % of a polyallylic compound or a polyol poly(meth)acrylate crosslinking agent;

(c) about 5 to about 60 wt % of glass fiber;

(d) about 5 to about 25 wt % of a flame retardant system comprising

i. a metal phosphinate salt, a metal diphosphinate salt, or a combination thereof; and

ii. optionally at least one nitrogen compound selected from the group consisting of condensation products of melamine and/or reaction products of condensation products of melamine with phosphoric acid, and/or mixtures thereof, melam, melem, melon, melamine cyanurate, melamine phosphate compounds, dimelamine phosphate, melamine pyrophosphate, benzoguanamine compounds, terepthalic ester compounds of tris(hydroxyethyl)isocyanurate, allantoin compounds, glycoluril compounds, ammeline, ammelide, and combinations thereof; and

(e) about 1 to 15 wt % of a flame retardant system coagent;

wherein all the amounts are based upon the total weight of the composition.

32. The composition of claim 31 , wherein the polyamide comprises about 15 to about 35 wt % nylon-6 and about 15 to about 35 wt % nylon-6,6;

(f) about 1 to about 10 wt % of a crosslinking agent selected from the group consisting of triallylisocyanurate, triallylcyanurate, ethyleneglycol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate;

(g) about 15 to about 30 wt % of glass fiber; and

(h) about 10 to about 20 wt % of the flame retardant system wherein the nitrogen compound is melamine, melamine phosphate, melamine pyrophosphate, or melamine polyphosphate;

wherein all the amounts are based upon the total weight of the composition.

33. A method of forming a crosslinkable, flame retardant composition comprising:

(i) blending a polyamide, a crosslinking agent, wherein the crosslinking agent comprises two or more groups capable of forming free radicals under beta or gamma radiation;

(j) a flame retardant system coagent, and

(k) a flame retardant system comprising

i. a metal phosphinate salt, a metal diphosphinate salt, or combination thereof; and

ii. optionally at least one nitrogen compound selected from the group consisting of condensation products of melamine and/or reaction products of condensation products of melamine with phosphoric acid, and/or mixtures thereof, melam, melem, melon, melamine, melamine cyanurate, melamine phosphate compounds, dimelamine phosphate, melamine pyrophosphate, melamine polyphosphate compounds, benzoguanamine compounds, terepthalic ester compounds of tris(hydroxyethyl)isocyanurate, allantoin compounds, glycoluril compounds, ammeline, ammelide, and combinations thereof, to form an intimate blend.

34. The method of claim 33 , further comprising molding the intimate blend into an article and crosslinking the composition with ionizing radiation.