Inorganic foam based on calcium sulfoaluminate

1. A process for preparing an inorganic foam comprising the steps of

(1) mixing

(i) at least one group of inorganic particles;

(ii) at least one amphiphilic compound;

(iii) at least one inorganic binder mixture comprising

(iiia) at least one calcium sulfoaluminate mixture, and optionally

(iiib) at least one further inorganic binder selected from the group consisting of hydraulic binders, latent hydraulic binders, pozzolanic binders, and mixtures thereof;

(iv) water; and optionally

(v) at least one additive; and

(2) foaming the resulting foam formulation by chemical, physical or mechanical foaming; wherein the at least one calcium sulfoaluminate mixture contains a) ye'elimite (4CaO×3Al 2 O 3 ×SO 3 ) and optionally belite (2CaO×SiO 2 ) and b) anhydrite (CaSO 4 ), calcium sulfate hemihydrate (CaSO 4 ×0.5H 2 O) and/or gypsum (CaSO 4 ×2H 2 O), in a weight ratio of a):b) of from 90:10 to 60:40.

2. The process according to claim 1 , wherein the at least one group of inorganic particles is selected from the group consisting of oxides, hydroxides, carbides, nitrides, phosphates, carbonates, silicates, sulfates, and mixtures thereof.

3. The process according to claim 1 , wherein the at least one group of inorganic particles is selected from the group consisting of silica particles, alumina particles, zirconia particles, CaCO 3 particles, and mixtures thereof.

4. The process according to claim 1 , wherein the at least one group of inorganic particles has a median particle size D 50 in the range of from 30 nm to 300 μm.

5. The process according to claim 1 , wherein the at least one amphiphilic compound comprises amphiphilic compounds with at least one polar head group and at least one apolar tail group,

wherein the at least one head group is selected from the group consisting of phosphates, phophonates, sulfates, sulfonates, alcohols, amines, amides, pyrrolidines, gallates, and carboxylic acids;

and wherein the at least one tail group is selected from an aliphatic or an aromatic or a cyclic group with 2 to 8 carbon atoms, wherein the carbon atoms are optionally substituted with one or more, same or different substituents selected from C 1 -C 8 -alkyl, secondary —OH, and secondary —NH 2 .

6. The process according to claim 1 , wherein the at least one amphiphilic compound comprises amphiphilic compounds with at least one head group selected from the group consisting of carboxylic acids, gallates and amines, and at least one tail group selected from aliphatic groups with 2 to 8 carbon atoms.

7. The process according to claim 1 , wherein the at least one calcium sulfoaluminate mixture has the analytical oxide composition of 5 to 35 wt.-% of SO 3 , 30 to 60 wt.-% of CaO, 0 to 30 wt.-% of SiO 2 and 5 to 35 wt.-% of Al 2 O 3 .

8. The process according to claim 1 , wherein the at least one further inorganic binder is selected from the group consisting of blast furnace slag, microsilica, metakaolin, aluminosilicates, fly ash, and mixtures thereof.

9. The process according to claim 1 , wherein the at least one further inorganic binder is a mixture of metakaolin and fly ash.

10. The process according to claim 1 , wherein the at least one inorganic binder mixture (iii) comprises

(iiic) at least one cement selected from CEM I, CEM II, CEM III, CEM IV, CEM V cements, according to DIN EN 197-1 (11/2011), or calcium aluminate cement.

11. The process according to claim 1 , wherein the at least one additive is selected from the group consisting of pH modifiers, fillers, accelerators, retarders, rheology modifiers, superplasticizers, surfactants, fibers, waterglass, further hydrophobization agents, catalysts, and mixtures thereof.

12. The process according to claim 1 , wherein the amount of amphiphilic compound to inorganic particle surface is from 0.5 to 160 μmol/m2; and/or

wherein the inorganic particles are provided in an amount of from 0.1 to 25 wt.-% with regard to the amount of the at least one inorganic binder mixture; and/or

wherein the weight ratio of water to the inorganic binder mixture is from 0.1 to 2.0.

13. The process according to claim 1 , wherein step (1) comprises the steps of (1a) dispersing the at least one group of inorganic particles, the at least one amphiphilic compound, and optionally the at least one additive in water to obtain an aqueous dispersion; and

(1b) mixing the aqueous dispersion with the at least one inorganic binder mixture.

14. An inorganic foam obtained by the process according to claim 1 .

15. A cellular material obtained by hardening and optionally drying an inorganic foam according to claim 14 .

16. An inorganic foam comprising

(i) at least one group of inorganic particles;

(ii) at least one amphiphilic compound;

(iii) at least one inorganic binder mixture comprising

(iiia) at least one calcium sulfoaluminate mixture, and optionally

(iiib) at least one further inorganic binder selected from the group consisting of hydraulic binders, latent hydraulic binders, pozzolanic binders, and mixtures thereof;

(iv) water; and optionally

(v) at least one additive;

wherein the at least one calcium sulfoaluminate mixture contains a) ye'elimite (4CaO×3Al 2 O 3 ×SO 3 ) and optionally belite (2CaO×SiO 2 ) and b) anhydrite (CaSO 4 ), calcium sulfate hemihydrate (CaSO 4 ×0.5H 2 O) and/or gypsum (CaSO 4 ×2H 2 O), in a weight ratio of a):b) of from 90:10 to 60:40.

17. The process according to claim 1 , wherein the at least one inorganic binder mixture (iii) comprises CEM I cement, according to DIN EN 197-1 (11/2011).

18. A cellular material obtained by hardening and optionally drying an inorganic foam according to claim 16 .

19. A composition for preparing an inorganic foam formulation comprising as components

(i) at least one group of inorganic particles;

(ii) at least one amphiphilic compound;

(iii) at least one inorganic binder mixture comprising

(iiia) at least one calcium sulfoaluminate mixture, and optionally

(iiib) at least one further inorganic binder selected from the group consisting of hydraulic binders, latent hydraulic binders, pozzolanic binders, and mixtures thereof;

wherein

the components (i), (ii), and (iii) are present separately; or the components (i) and (ii) are present as a mixture and the component (iii) is present separately; or

the components (i), (ii) and (iii) are present as a mixture;

wherein the at least one calcium sulfoaluminate mixture contains a) ye'elimite (4CaO×3Al 2 O 3 ×SO 3 ) and optionally belite (2CaO×SiO 2 ) and b) anhydrite (CaSO 4 ), calcium sulfate hemihydrate (CaSO 4 ×0.5H 2 O) and/or gypsum (CaSO 4×2 H 2 O), in a weight ratio of a):b) of from 90:10 to 60:40.

20. A process for preparing an inorganic foam comprising the steps of

(1) mixing

(i) at least one group of inorganic particles;

(ii) at least one amphiphilic compound;

(iii) at least one inorganic binder mixture comprising

(iiia) at least one calcium sulfoaluminate mixture, and optionally

(iiib) at least one further inorganic binder selected from the group consisting of hydraulic binders, latent hydraulic binders, pozzolanic binders, and mixtures thereof;

(iv) water; and optionally

(v) at least one additive; and

(2) foaming the resulting foam formulation by chemical, physical or mechanical foaming;

wherein the at least one further inorganic binder is a mixture of metakaolin and fly ash.

21. A process for preparing an inorganic foam comprising the steps of

(1) mixing

(i) at least one group of inorganic particles;

(ii) at least one amphiphilic compound;

(iii) at least one inorganic binder mixture comprising

(iiia) at least one calcium sulfoaluminate mixture, and optionally

(iiib) at least one further inorganic binder selected from the group consisting of hydraulic binders, latent hydraulic binders, pozzolanic binders, and mixtures thereof;

(iv) water; and optionally

(v) at least one additive; and

(2) foaming the resulting foam formulation by chemical, physical or mechanical foaming;

wherein the at least one inorganic binder mixture (iii) comprises

(iiic) at least one cement selected from CEM I, CEM II, CEM III, CEM IV, CEM V cements, according to DIN EN 197-1 (11/2011), or calcium aluminate cement.

22. A process for preparing an inorganic foam comprising the steps of

(1) mixing

(i) at least one group of inorganic particles;

(ii) at least one amphiphilic compound;

(iii) at least one inorganic binder mixture comprising

(iiia) at least one calcium sulfoaluminate mixture, and optionally

(iiib) at least one further inorganic binder selected from the group consisting of hydraulic binders, latent hydraulic binders, pozzolanic binders, and mixtures thereof;

(iv) water; and optionally

(v) at least one additive; and

(2) foaming the resulting foam formulation by chemical, physical or mechanical foaming;

wherein step (1) comprises the steps of

(1a) dispersing the at least one group of inorganic particles, the at least one amphiphilic compound, and optionally the at least one additive in water to obtain an aqueous dispersion; and

(1b) mixing the aqueous dispersion with the at least one inorganic binder mixture.