Process for the manufacture of a grease composition

1. A process for the manufacture of a metal complex grease composition comprising the steps of:

(i) preparing a slurry comprising a base oil, water, a metal base and a complexing agent, wherein the weight ratio of water:solid in the slurry is in the range of from 0.15:1 to 1.5:1;

(ii) applying shear to the slurry at a shear frequency of at least 1,000,000 s −1 ;

(iii) adding the slurry emerging from step (ii) to a C 10 -C 24 saturated or unsaturated fatty acid or derivative thereof to effect a saponification reaction, the saponification reaction being carried out at a temperature of at least 80° C.;

(iv) removing water from the saponified product resulting from step (iii);

(v) heating the product emerging from step (iv) at a temperature in the range of from 190 to 230° C.; and

(vi) cooling the product emerging from step (v) to a temperature in the range of from 200 to 150° C. to form the metal complex grease composition.

2. The process according to claim 1 wherein the weight ratio of water:solid in the slurry is in the range of from 0.2:1 to 1:1.

3. The process according to claim 1 wherein the shear frequency is at least 1,500,000 s −1 .

4. The process according to claim 1 wherein step (ii) is carried out by a high shear mixer having at least one square holes screen.

5. The process according to claim 4 wherein the high shear mixer comprises two square holes screens.

6. The process according to claim 1 wherein the process comprises an additional step (vii):

(vii) adding performance additives to the metal complex grease composition.

7. The process according to claim 1 wherein the metal base is selected from the group consisting of: lithium hydroxide, calcium hydroxide, aluminium hydroxide, titanium hydroxide and mixtures thereof.

8. The process according to claim 1 wherein the metal base is lithium hydroxide.

9. The process according to claim 1 wherein the complexing agent is selected from the group consisting of: boric acid, sebacic acid, azelaic acid, benzoic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, pimelic acid, dodecanedioic acid, and mixtures thereof.

10. The process according to claim 1 wherein the complexing agent is boric acid.

11. The process according to claim 1 wherein the C 10 -C 24 saturated or unsaturated fatty acid or derivative thereof is 12-hydroxy stearic acid.