Production of anionic detergent particles

Abstract

In a process for producing detergent particles comprising an anionic surfactant, a paste comprising water and the surfactant is fed to a drying zone where it is heated. Subsequently, the paste is cooled in a cooling zone. A layering agent is introduced into the cooling zone to improve granularity.

I claim: 
     
       1. A process for producing detergent particles comprising an anionic surfactant, the process comprising the steps of feeding a paste material comprising water and an anionic surfactant into a scrape surface drier comprising a drying zone, heating the paste material in the drying zone for an average residence time of less than 5 minutes to reduce the water content thereof and subsequently cooling the paste material in a cooling zone operated at a temperature not in excess of 50° C. to form detergent particles, characterized by introducing a layering agent into the cooling zone during the cooling step. 
     
     
       2. A process for producing detergent particles comprising an anionic surfactant, the process comprising the steps of feeding a paste material comprising water and an anionic surfactant into a scrape surface drier comprising a drying zone, heating the paste material in the drying zone for an average residence time of less than 5 minutes to reduce the water content thereof and subsequently cooling the paste material in a cooling zone operated at a temperature not in excess of 50° C. to form detergent particles, characterized by treating the paste material in the cooling zone with a stream of cooling gas. 
     
     
       3. The process according to claim 1, wherein the anionic surfactant comprises a linear alkylbenzene sulphonate. 
     
     
       4. The process according to claim 2, wherein the anionic surfactant comprises a linear alkylbenzene sulphonate. 
     
     
       5. The process according to claim 3, wherein the linear alkylbenzene sulphonate comprises from 10% to 100% by weight of the total anionic surfactant. 
     
     
       6. The process according to claim 4, wherein the linear alkylbenzene sulphonate comprises from 10% to 100% by weight of the total anionic surfactant. 
     
     
       7. The process according to claim 4, wherein the paste material comprises no more than 50% by weight of water. 
     
     
       8. The process according to claim 2, wherein the paste material comprises no more than 50% by weight of water. 
     
     
       9. The process according to claim 1, wherein the layering agent comprises an aluminosilicate, a silica or a mixture thereof. 
     
     
       10. The process according to claim 2, wherein the layering agent comprises an aluminosilicate, a silica or a mixture thereof. 
     
     
       11. The process according to claim 1, wherein the layering agent is dosed into the cooling zone at a weight ratio of from 1:5 to 1:20 relative to the finished particles. 
     
     
       12. The process according to claim 1, wherein the anionic surfactant is formed by admixture of the free acid form of the anionic surfactant and a neutralising agent. 
     
     
       13. The process according to claim 2, wherein the anionic surfactant is formed by admixture of the free acid form of the anionic surfactant and a neutralising agent. 
     
     
       14. The process according to claim 1, wherein the resultant particles comprise at least 75% by weight of the anionic surfactant and no more than 10% by weight of water. 
     
     
       15. The process according to claim 2, wherein the resultant particles comprise at least 75% by weight of the anionic surfactant and no more than 10% by weight of water. 
     
     
       16. The process according to claim 1, wherein the resultant particles have a D(4,3) average particle diameter of from 180 to 1500 microns. 
     
     
       17. The process according to claim 2, wherein the resultant particles have a D(4,3) average particle diameter of from 180 to 1500 microns. 
     
     
       18. Detergent particles comprising at least 60% by weight of the particle of an anionic surfactant, and not more than 5% by weight of the particle of water, the particles being coated with a layering agent obtainable by a process according to any preceding claim. 
     
     
       19. Detergent particles comprising an anionic surfactant, in an amount of at least 60% by weight of the particle, wherein the particles are coated with a layering agent and have a porosity of from 0% to 25% by volume of the particle and a particle size distribution such that at least 80% of the particles have a particle size of 180 to 1500 microns. 
     
     
       20. The particles according to claim 18, wherein the anionic surfactant comprises a linear alkylbenzene sulphonate. 
     
     
       21. The particles according to claim 19, wherein the anionic surfactant comprises a linear alkylbenzene sulphonate.