Flame retardant clear coatings for building panels

1. A flame-retardant coating composition comprising:

a coating comprising a first sub-layer, a second sub-layer atop the first sub-layer, and a third sub-layer atop the second sub-layer;

wherein the first sub-layer is an organic coating and comprises polymer produced from unsaturated monomers and the second sub-layer is an inorganic coating comprising aluminum carbonate, triethanolamine, and a blend of a first borate compound and a first phosphate compound;

wherein the aluminum carbonate is present in an amount of about 2.8 to about 4.8 wt. %;

wherein a weight ratio of first phosphate compound to the first borate compound within the second sub-layer is from about 5:1 to about 80:1;

wherein the third sub-layer is an inorganic coating composition comprising triethanolamine, a second borate compound, and a second phosphate compound; and

wherein the second borate compound is zinc borate and the first borate compound is boron trioxide.

2. The flame-retardant coating of claim 1 , wherein the flame-retardant coating composition is optically transparent.

3. The flame-retardant coating of claim 1 , wherein the inorganic coating has a maximum pH of about 5.

4. The flame-retardant coating of claim 1 , wherein the inorganic coating comprises up to about 5 wt. % of organic components based on the total weight of the inorganic coating.

5. The flame-retardant coating of claim 1 , wherein the first borate compound is present in an amount of about 0.5 wt. % to about 15.0 wt. %, based on the total dry weight of the second sub-layer.

6. The flame-retardant coating of claim 1 , wherein the first sub-layer comprises an organic component selected from the group consisting of a wax emulsion, latex polymer, and combinations thereof.

7. The flame-retardant coating of claim 1 , wherein the second sub-layer and the third sub-layer comprise calcium carbonate.

8. The composition of claim 1 , wherein the first phosphate compound is present in an amount from about 55.0 wt. % to about 75.0 wt. %, based on the total weight of the second sub-layer in the dry-state, and wherein the first borate compound is present in an amount of about 1 wt. % to about 10.5 wt. %, based on the total weight of the second sub-layer in the dry-state.

9. The composition of claim 1 , further comprising silicon dioxide.

10. A flame-retardant coating composition comprising:

a coating comprising a first sub-layer, a second sub-layer atop the first sub-layer, and a third sub-layer atop the second sub-layer;

wherein the second sub-layer comprises an inorganic component comprising aluminum carbonate, triethanolamine, a filler comprising magnesium carbonate and calcium carbonate, and a blend of a first borate compound and a first phosphate compound comprising phosphoric acid;

wherein the third sub-layer comprises a second inorganic component comprising triethanolamine, magnesium carbonate, and a blend of a second borate compound that is different from the first borate compound and a second phosphate compound;

wherein the aluminum carbonate is present in an amount from about 2.8 to about 4.8 wt. %;

wherein the coating composition has a maximum pH of 5 and comprises up to about 5.0 wt. % of organic components based on the total weight of the coating composition;

wherein the composition is free of carrier;

wherein the first borate compound is boron trioxide and the second borate compound is zinc borate;

wherein a weight ratio of phosphate to the borate compound within the inorganic component of the second sub-layer is from about 5:1 to about 80:1;

wherein the flame-retardant coating composition is optically transparent.

11. The composition of claim 10 , wherein the triethanolamine is present in an amount ranging from a non-zero amount to less than 5.0 wt. %, based on the total weight of the coating composition.

12. The composition of claim 10 , wherein the composition comprises up to about 1.0 wt. % of organic components, based on the total weight of the coating composition.

13. The composition of claim 10 , wherein the first phosphate compound is present in an amount from about 55.0 wt. % to about 75.0 wt. %, based on the total weight of the coating composition, and wherein the first borate compound is present in an amount of about 1 wt. % to about 10.5 wt. %, based on the total weight of the coating composition.

14. The composition of claim 10 , further comprising silicon dioxide.