Warewashing system containing nonionic surfactant that performs both a cleaning and sheeting function and a method of warewashing

Abstract

We have found an alkaline warewashing detergent composition that can contain a critical amount of a nonionic rinse agent that when used in automatic warewashing machines permits the use of a potable water rinse without the addition of a separate rinse agent. Sufficient residual nonionic surfactant from the alkaline detergent remains on the surface ware and internal machine and rack surfaces after washing to promote adequate sheeting in the rinse cycle. The residual nonionic surfactant on internal surfaces dissolves in the rinse water to create an effective aqueous rinse agent. The nonionic rinse agents can be a single nonionic for both foam reduction cleaning and sheeting or can be a blend of nonionic materials providing these functions. The detergent can be in the form of a particulate, pelletized or block solid. The detergent can be used in a variety of high temperature and low temperature automatic warewashing machines including large multizone conveyor machines, or relatively small institutional machines that have a single washing chamber.

We claim:  
     
       1. A method of washing ware, using a cleaning composition containing a nonionic rinse agent composition to both wash and rinse, the method comprising: 
       (a) contacting ware with an aqueous cleaning composition, in an automatic warewashing machine, the aqueous cleaning composition comprising a major proportion of an aqueous diluent and about 250 to 3000 parts by weight of an alkaline warewashing detergent per each one million parts of the aqueous diluent, the detergent comprising:  
       (i) about 0.1 to 60 wt-% of a source of alkalinity;  
       (ii) at least about 30 wt-% of nonionic surfactant having at least one block segment comprising  
       -(AO) x -;  
       wherein AO represents an oxyalkylene moiety and x is a number of about 1 to 100; and 
       (b) contacting the washed ware with a potable aqueous rinse, the aqueous rinse being substantially free of an intentionally added rinse agent, to remove an aqueous residue;  
       wherein the alkaline warewashing detergent contains sufficient nonionic surfactant to provide adequate sheeting action in the potable aqueous rinse.  
     
     
       2. The method of  claim 1  wherein the potable aqueous rinse is recycled and combined with the warewashing detergent to form the aqueous cleaning composition. 
     
     
       3. The method of  claim 1  wherein the aqueous cleaning composition comprises about 800 to 1800 parts of the alkaline detergent per each million parts of aqueous diluent. 
     
     
       4. The method of  claim 3  wherein the potable aqueous rinse, after it is used, is directed to a machine discharge and the aqueous cleaning composition, after use, is directed to a machine discharge. 
     
     
       5. The method of  claim 1  wherein the temperature of the aqueous cleaning composition is about 30° C. to 65° C. 
     
     
       6. The method of  claim 1  wherein the temperature of the aqueous cleaning composition is about 65° C. to 85° C. 
     
     
       7. The method of  claim 1  wherein the temperature of the rinse is about 30° C. to 65° C. 
     
     
       8. The method of  claim 1  wherein the source of alkalinity is sodium hydroxide present at a concentration of about 0.1 to 35 wt-%. 
     
     
       9. The method of  claim 1  wherein the source of alkalinity is Na 2 CO 3  present at a concentration of about 5 to 50 wt %. 
     
     
       10. The composition of  claim 1  wherein the nonionic surfactant comprises a block polymeric surfactant. 
     
     
       11. The method of  claim 1  wherein the nonionic surfactant comprises a alcohol ethoxylate comprising the formula segment: 
       
         
           C 6-24 Alkyl-O-(EO) x -  
         
       
       wherein EO is an oxyethylene moiety and x is 1-100. 
     
     
       12. The method of  claim 1  wherein the nonionic surfactant comprises a benzyl capped alcohol ethoxylate comprising the formula: 
       
         
           C 6-24 Alkyl-O-(EO) x -Bz  
         
       
       wherein EO is an oxyethylene moiety, Bz is benzyl and x is 2-25. 
     
     
       13. The method of  claim 1  wherein the nonionic surfactant comprises a nonionic block polymeric surfactant having the formula: 
       
         
           HO-(PO)hd y-(EO) x -(PO) y -H  
         
       
       wherein PO is oxypropylene, EO is oxyethylene, x and y are independently 1-100. 
     
     
       14. The method of  claim 1  wherein the nonionic surfactant comprises a nonionic block polymeric surfactant having the formula: 
       
         
           HO-(PO) y -(EO) x -(PO) z -(EO) x -(PO) y -H  
         
       
       wherein PO is oxypropylene, EO is oxyethylene and x, y and z are independently about 1-100. 
     
     
       15. The method of  claim 14  wherein the (PO) z  moiety comprises a heteric block comprising a propylene glycol residue, about 1-5 moles EO and about 20-30 moles PO. 
     
     
       16. The method of  claim 1  wherein the warewashing detergent is a solid detergent formed in a capsule comprising a thermoplastic. 
     
     
       17. The method of  claim 16  wherein the weight of the solid detergent is about 0.25 to 10 kilograms. 
     
     
       18. A method of washing ware using a cleaning composition using a solid block nonionic composition to both wash and rinse, the method comprising: 
       (a) contacting ware with aqueous cleaning composition in an automatic warewashing machine, the aqueous cleaning composition comprising a major proportion of water and an alkaline warewashing detergent comprising:  
       (i) about 1 to 60 wt-% of an alkali metal carbonate or bicarbonate;  
       (ii) at least about 30 wt-% of a first block polymer nonionic surfactant having at least one block segment comprising:  
       an -(EO) x - segment, a -(PO) y -segment or both;  
       wherein EO represents an oxyethylene moiety and PO represents an oxypropylene moiety, x and y are integers of 1-100; and  
       wherein the solid block nonionic composition is substantially free of both an alkali metal hydroxide and an alkali metal silicate and each weight percent is based on the solid block nonionic composition; and  
       (b) contacting the washed ware with a potable aqueous rinse, the rinse being substantially free of an intentionally added rinse agent to remove any resinable residue; wherein the alkaline warewashing detergent contains sufficient nonionic surfactant to provide adequate sheeting action in the potable aqueous rinse.  
     
     
       19. The method of  claim 18  wherein the alkali metal carbonate is sodium carbonate present at a concentration of about 5 to 50 wt-%. 
     
     
       20. The method of  claim 18  wherein the warewashing detergent comprises a second nonionic surfactant comprising a benzyl capped alcohol ethoxylate of the formula: 
       
         
           C 6-24 Alkyl-O-(EO) x -Bz  
         
       
       wherein EO is an oxyethylene moiety, Bz is benzyl and x is 1-100. 
     
     
       21. The method of  claim 18  wherein the nonionic surfactant is of the formula: 
       
         
           HO-(PO)hd y-(EO) x -(PO) y -H  
         
       
       wherein PO is oxypropylene, EO is oxyethylene, x and y are independently 1-100. 
     
     
       22. The method of  claim 18  wherein the nonionic surfactant comprises a nonionic block polymeric surfactant having the formula: 
        HO-(PO) y -(EO) x -(PO) z -(EO) x -(PO) y -H 
       wherein PO is oxypropylene, EO is oxyethylene and x, y and z are independently about 1-100. 
     
     
       23. The method of  claim 22  wherein the (PO) z  moiety comprises a heteric block comprising a propylene glycol residue, about 1-5 moles EO and about 20-30 moles PO. 
     
     
       24. The method of  claim 18  wherein the solid block nonionic composition is formed in a capsule comprising a thermoplastic. 
     
     
       25. The method of  claim 18  wherein the weight of the solid block nonionic composition is about 0.25-10 kilograms. 
     
     
       26. The method of  claim 25  wherein the composition comprises about 0.1 to 30 wt-% of a urea solidification agent. 
     
     
       27. A method of washing ware, using a cleaning composition containing a rinse agent, the method comprising steps of: 
       ( a )  washing ware with an aqueous cleaning composition, in an automatic warewashing machine, the aqueous cleaning composition comprising a major proportion of an aqueous diluent and a sufficient amount of an alkaline warewashing detergent to adequately clean the ware while leaving a sufficient concentration of a rinse agent residue on the ware, the detergent comprising:    
       ( i )  about  0 . 1  to  60  wt -%  of a source of alkalinity;    
       ( ii )  rinse agent, comprising a nonionic material, in an amount sufficient to provide an aqueous residue on the ware as a result of the step of washing that contains sufficient rinse agent to provide sheeting action when the ware is rinsed with a potable aqueous rinse; and    
       ( b )  rinsing the washed ware with a potable aqueous rinse, the potable aqueous rinse being substantially free of an intentionally added rinse agent, to remove an aqueous residue.   
     
     
       28. The method of  claim 27  wherein the potable aqueous rinse is recycled and combined with the warewashing detergent to form the aqueous cleaning composition. 
     
     
       29. The method of  claim 27  wherein the aqueous cleaning composition comprises about  800  to  1800  parts of the alkaline detergent per each million parts of aqueous diluent. 
     
     
       30. The method of  claim 29  wherein the potable aqueous rinse, after it is used, is directed to a machine discharge and the aqueous cleaning composition, after use, is directed to a machine discharge. 
     
     
       31. The method of  claim 27  wherein the temperature of the aqueous cleaning composition is about  30 ° C. to  65 ° C. 
     
     
       32. The method of  claim 27  wherein the temperature of the aqueous cleaning composition is about  65 ° C. to  85 ° C. 
     
     
       33. The method of  claim 27  wherein the temperature of the rinse is about  30 ° C. to  65 ° C. 
     
     
       34. The method of  claim 27  wherein the source of alkalinity is sodium hydroxide present at a concentration of about  0 . 1  to  35  wt-% .   
     
     
       35. The method of  claim 27  wherein the source of alkalinity is Na 2   CO   3    present at a concentration of about  5  to  50  wt  % .   
     
     
       36. The method of  claim 27 , wherein the rinse agent comprises a nonionic surfactant having at least one block segment comprising 
       
         
           -( AO ) x -  
         
       
       
         wherein AO represents an oxyalkylene moiety and x is a number of about  1  to  100 . 
       
     
     
       37. The composition of  claim 27 , wherein the rinse agent comprises at least one of polyoxyethylene ( ethoxylate )  surfactants, carboxylic acid ester surfactants, carboxylic acid amide surfactants, hydrophobically substituted oxyalkylene surfactants, and polyalkylene oxide block copolymers.   
     
     
       38. The method of  claim 36  wherein the nonionic surfactant comprises an alcohol ethoxylate comprising the formula segment: 
       
         
             C   6-24   Alkyl - O -( EO ) x -  
         
       
       
         wherein EO is an oxyethylene moiety and x is  1 - 100 . 
       
     
     
       39. The method of  claim 36  wherein the nonionic surfactant comprises a benzyl capped alcohol ethoxylate comprising the formula: 
       
         
             C   6-24   Alkyl - O -( EO ) x - Bz    
         
       
       
         wherein EO is an oxyethylene moiety, Bz is benzyl and x is  2 - 25 . 
       
     
     
       40. The method of  claim 36  wherein the nonionic surfactant comprises a nonionic block polymeric surfactant having the formula: 
       
         
             HO -( PO ) y -( EO ) x -( PO ) y - H    
         
       
       
         wherein PO is oxypropylene, EO is oxyethylene, x and y are independently  1 - 100 . 
       
     
     
       41. The method of  claim 36  wherein the nonionic surfactant comprises a nonionic block polymeric surfactant having the formula: 
       
         
             HO -( PO ) y -( EO ) x -( PO ) z -( EO ) x -( PO ) y - H    
         
       
       
         wherein PO is oxypropylene, EO is oxyethylene and x, y and z are independently about  1 - 100 . 
       
     
     
       42. The method of  claim 41  wherein the ( PO ) z    moiety comprises a heteric block comprising a propylene glycol residue, about  1 - 5  moles EO and about  20 - 30  moles PO.   
     
     
       43. The method of  claim 41  wherein the warewashing detergent is a solid detergent formed in a capsule comprising a thermoplastic. 
     
     
       44. The method of  claim 43  wherein the weight of the solid detergent is about  0 . 25  to  10  kilograms.