Water-soluble glass as corrosion protector in dishwashing machines

Abstract

A zinc-containing, water-soluble glass composition comprising from 41 to 54 mole % of P 2 O 5 , 10 to 30 mole % of alkali oxides, up to 5 mole % of SO 3 and up to 25 mole % of ZnO.

1 . A zinc-containing, water-soluble glass composition comprising: 
 from 41 to 54 mole % of P 2 O 5 ,    10 to 30 mole % of alkali oxides,    up to 5 mole % of SO 3  and    up to 25 mole % of ZnO.    
     
     
         2 . The composition according to  claim 1  characterised in that not more than 40 mole % of the total amount of alkali oxides in the composition is constituted by one or more members of the group consisting of Li 2 O and Na 2 O.  
     
     
         3 . The composition according to  claim 1  characterised in that the composition additionally comprises at least one alkaline-earth oxide with a total amount of alkaline-earth oxides of less than 20 mole %.  
     
     
         4 . The composition according to  claim 1  characterised in that the composition additionally comprises at least one oxide of antimony or arsenic present in the composition in an amount of of less than 5 mole %.  
     
     
         5 . The composition according to  claim 1  characterised in that the composition additionally comprises at least one oxide of an element from the group consisting of silicium, germanium, tin and lead present in the composition in an amount of with a total amount of such oxides of less than 10 mole %.  
     
     
         6 . The composition according to  claim 1  characterised in that the composition it additionally comprises at least one oxide of an element selected from the group consisting of silicon, aluminium and boron present in the composition in an amount of from 0. 1 to 10 mole.  
     
     
         7 . The composition according to  claim 1  characterised in that the composition does not comprise more than 0.5 mole-% of oxides of elements from the group IIIb of the Periodic System of Elements.  
     
     
         8 . The composition according to  claim 1  characterised in that the composition comprises 
 from 41 to 54 mole % of P 2 O 5 ,    from 10 to 30 mole % of alkali oxides,    up to 5 mole % of SO 3 ,    up to 25 mole % of ZnO,    less than 5 mole % alkaline-earth oxides, and    from 0.3 to 3 mole % of oxides of elements selected from the group consisting of silicon, aluminium and boron.    
     
     
         9 . The composition according to  claim 1  characterised in that the composition is present in the form of a transparent shaped body.  
     
     
         10 . The composition according to  claim 9  characterised in that the shaped body is manufactured by continuous glass manufacturing processes.  
     
     
         11 . The composition according to  claim 1  any of claims  1  to 8 characterised in that the composition it is present in a comminuted form.  
     
     
         12 . The composition according to  claim 11  characterised in that the composition is manufactured by the breaking of thin glass plates.  
     
     
         13 . The composition according to  claim 11  characterised in that the composition is manufactured by a process which includes a milling step.  
     
     
         14 . The composition according to  claim 13 , characterised in that the milled glass has an average particle size of not more than 500 microns.  
     
     
         15 . A process for the inhibition of corrosion of glassware in an automatic dishwashing process which comprises the step of: contacting said glassware with a zinc-containing, water-soluble glass composition according to  claim 1 .  
     
     
         16 . A process for the inhibition of corrosion of glassware in an automatic dishwashing process characterised by: 
 providing a zinc-containing, water-soluble glass composition according to  claim 1  at an appropriate place within an automatic dishwashing machine wherein the said composition is accessible to the wash liquor and/or rinse water.    
     
     
         17 . A process for the inhibition of corrosion of glassware in an automatic dishwashing process characterised by: 
 contacting the glassware, in an automatic dishwashing machine, with wash liquor and/or rinse water containing an effective amount of a composition according to  claim 1 .    
     
     
         18 . A process for the inhibition of corrosion of glassware in an automatic dishwashing process characterised by: 
 providing a zinc-containing, water-soluble glass composition according to  claim 9  at an appropriate place within an automatic dishwashing machine wherein the said composition is accessible to the wash liquor and/or rinse water.    
     
     
         19 . A process for the inhibition of corrosion of glassware in an automatic dishwashing process characterised by: 
 contacting the glassware, in an automatic dishwashing machine, with wash liquor and/or rinse water containing an effective amount of a composition according to  claim 11.