Flame retardant composition

1. A flame retardant composition comprising:

a. a polyolefin polymer; and

b. a three-component flame retardant additive consisting essentially of

(i) a nano-silicate present in an amount between 0.1% and 15% by weight;

(ii) a metal hydroxide; and

(iii) calcium carbonate,

wherein the calcium carbonate is present in an amount less than or equal to the amount of the metal hydroxide.

2. The flame-retardant composition of claim 1 wherein the polyolefin polymer is selected from the group consisting of ethylene polymers and propylene polymers.

3. The flame-retardant composition of claim 1 wherein the nano-silicate is a layered nano-silicate.

4. The flame retardant composition of claim 3 wherein the nano-silicate is selected from the group consisting of montmorillonite, magadiite, fluorinated synthetic mica, saponite, fluorhectorite, laponite, sepiolite, attapulgite, hectorite, beidellite, vermiculite, kaolinite, nontronite, volkonskoite, stevensite, pyrosite, sauconite, and kenyaite.

5. The flame-retardant composition of claim 4 wherein the nano-silicate is selected from the group consisting of montmorillonite and magadiite.

6. The flame-retardant composition of claim 3 wherein the nano-silicate is treated with an organic cation.

7. The flame-retardant composition of claim 6 wherein the organic cation is selected from the group consisting of imidazolium, phosphonium, ammonium, alkyl ammonium, and polyalkyl ammonium.

8. The flame-retardant composition of claim 1 wherein the metal hydroxide is selected from the group consisting of aluminum trihydroxide and magnesium hydroxide.

9. The flame retardant composition of claim 1 wherein a surface of the metal hydroxide is coated with a material selected from the group consisting of silanes, titanates, zirconates, carboxylic acids, and maleic anhydride-grafted polymers.

10. The flame retardant composition of claim 1 wherein a surface of the calcium carbonate is coated with a material selected from the group consisting of silanes, titanates, zirconates, carboxylic acids, and maleic anhydride-grafted polymers.

11. A coating composition prepared from the flame-retardant composition of claim 1 .

12. A flame-retardant wire or cable construction prepared by applying the coating composition of claim 11 over a wire or cable.

13. An article comprising the flame-retardant composition of claim 1 , where the article is selected from the group consisting of extruded sheets, thermoformed sheets, injection-molded articles, coated fabrics, roofing membranes, and wall coverings.

14. A flame retardant composition comprising:

a. a polyolefin polymer selected from the group consisting of ethylene polymers and propylene polymers;

b. a three-component flame retardant additive consisting essentially of

(i) a layered nano-silicate selected from the group consisting of montmorillonite and magadiite and being present in an amount between 0.1% and 15% by weight;

(ii) a metal hydroxide selected from the group consisting of aluminum trihydroxide and magnesium hydroxide; and

(iii) calcium carbonate,

wherein the calcium carbonate is present in an amount less than or equal to the amount of the metal hydroxide.

15. A coating composition prepared from the flame-retardant composition of claim 14 .

16. A flame-retardant wire or cable construction prepared by applying the coating composition of claim 15 over a wire or cable.

17. An article comprising the flame-retardant composition of claim 14 , where the article is selected from the group consisting of extruded sheets, thermoformed sheets, injection-molded articles, coated fabrics, roofing membranes, and wall coverings.