Production of anionic surfactant granules by in situ neutralization

Abstract

A process for producing granules of anionic surfactant, preferably PAS by in situ neutralisation of a precursor acid to form the surfactant, heating the surfactant to a temperature in excess of 130° C. and subsequently cooling the to provide surfactant granules is disclosed. Detergent compositions containing such granules are also disclosed.

We claim:  
     
       1. A process for the production of detergent particles consisting essentially of at least 50%, by weight of an anionic surfactant and no more than 20% by weight of water which comprises contacting a pumpable precursor acid of an anionic surfactant with a pumpable aqueous neutralising agent in a drying zone to produce an anionic surfactant the total water content being in excess of 20% by weight, heating the surfactant in the said drying zone to reduce the water content to not more than 20% by weight, to a temperature from 130° to 170° C. and subsequently cooling the surfactant to form detergent particles. 
     
     
       2. A process for the production of detergent particles consisting essentially of at least 50% by weight of an anionic surfactant and no more than 20% by weight of water which comprises contacting a pumpable precursor acid of an anionic surfactant with a pumpable neutralising agent in a drying zone to produce an anionic surfactant, to total water content being in excess of 20% by weight, agitating the precursor and neutralising agent with agitation means which have a tip speed in excess of 15 ms −1  heating the surfactant to a temperature from 130° to 170° C. in the said drying zone to reduce the water content to not more than 20% by weight and subsequently cooling the surfactant to form detergent particles. 
     
     
       3. Detergent particles comprising at least 60% by weight of the particle of an anionic surfactant and not more than 15% by weight of the particle of water, the particles being obtainable by a process according to the process according to  claim 1 . 
     
     
       4. Detergent particles according to  claim 3  comprising an anionic surfactant, wherein the particles have a porosity of 5 to 50% volume of the particles and a particles size distribution such that at least 80% of the particles have a particle size of 180 to 1500 microns, and less than 10% of the particles have a particles size less than 180 μm. 
     
     
       5. A detergent composition comprising detergent particles as defined in  claim 3  and a base powder comprising at least one of a surfactant and a builder. 
     
     
       6. A detergent composition according to claims  5  in which the base powder comprises a builder comprising a silicate. 
     
     
       7. A detergent composition according to  claim 5  which further comprises an alkali metal percarbonate. 
     
     
       8. A process for the production of detergent particles consisting essentially of at least  50 %  by weight of an anionic surfactant and no more than  20   %  by weight of water which comprises:    
         contacting a pumpable precursor acid of an anionic surfactant with a pumpable aqueous neutralising agent solution or slurry, wherein the neutralising agent is present in an amount of  25 - 55   %  by weight of the aqueous solution or slurry, in a drying zone comprising a heating jacket to produce an anionic surfactant, the total water content being in excess of  10   %  by weight,    
         heating the surfactant in the said drying zone to reduce the water content to not more than  20   %  by weight, to a temperature from  130 ° to  170 ° C.;    
       
         and subsequently cooling the surfactant to form detergent particles. 
       
     
     
       9. A process for the production of detergent particles consisting essentially of at least  50 %  by weight of an anionic surfactant and nor more than  20   %  by weight of water which comprises:    
         contacting a pumpable precursor acid of an anionic surfactant with a pumpable aqueous neutralising agent solution or slurry, wherein the neutralising agent is present in an amount of  25 - 55   %  by weight of the solution or slurry, in a drying zone comprising a heating jacket to produce an anionic surfactant, the total water content being in excess of  10   %  by weight, agitating the precursor and neutralising agent with agitation means which have a tip speed in excess of  15  ms   −1   ;    
         heating the surfactant to a temperature from  130 ° to  170 ° C. in the said drying zone to reduce water content to not more than  20   %  by weight;    
       
         and subsequently cooling the surfactant to form detergent particles.