Coating composition which adsorbs adourous and harmful substances and is intended for the box casting of metals

1. A casting mould for the casting of metals, comprising a layer of a material which absorbs harmful substances and is permeable to gas is arranged on at least sections of gas outlet surfaces on the outer surface of the casting mould.

2. The casting mould according to claim 1 , wherein the layer of a material which absorbs harmful substances has a thickness of at least 2.5 mm.

3. The casting mould according to claim 1 , wherein the layer of a material which absorbs harmful substances comprises at least one physical adsorber material which can physically adsorb harmful substances.

4. The casting mould according to claim 3 , wherein the physical adsorber material has a specific surface area of at least 800 m 2 /g.

5. The casting mould according to claim 3 , wherein the physical adsorber material is selected from activated charcoal, silica gel, clays digested by an acid, ashes, cellulose, rayon staple.

6. The casting mould according to claim 1 , wherein the layer of a material which absorbs harmful substances contains at least one chemical absorber material, which can bind or decompose harmful materials by a chemical reaction.

7. The casting mould according to claim 6 , wherein the chemical absorber material is a basic material.

8. The casting mould according to claim 7 , wherein the basic material is selected from oxides, hydroxides and carbonates of the alkali metals and alkaline-earth metals.

9. The casting mould according to claim 1 , wherein the layer of a material which absorbs harmful substances contains at least one refractory material which has an average grain size of at least 100 μm.

10. The casting mould according to claim 1 , wherein the layer of a material which absorbs harmful substances comprises a porous supporting framework.

11. A process for producing a casting mould comprising:

preparing a moulding material mixture comprising at least one refractory moulding material and at least one binder; and

molding the moulding material mixture into the casting mould, wherein gas outlet surfaces on the outer surface of the casting mould are covered at least in sections with a layer of a material which absorbs harmful substances and is permeable to gas.

12. The process according to claim 11 , wherein the layer of a material which absorbs harmful substances is provided by applying a porous supporting framework to at least sections of the gas outlet surfaces of the casting mould.

13. The process according to claim 11 , wherein the at least one binder is an organic binder.

14. The casting mould according to claim 1 , wherein the layer of a material which absorbs harmful substances has a thickness of at least 5 mm.