Deinking system for carbonate pulping

Abstract

A process for deinking paper being recycled in a carbonate pulping procedure which is performed in the absence of hydroxides and peroxides is improved by the addition of (a) a non-ionic surfactant deinking agent having a cloud point of about 55 to 85, preferably 60-70, and (b) at least two different fatty acid ink collectors: (i) a C16 to C20 fatty acid and (ii) a C22 to C30 fatty acid, the ink collectors being used in a weight ratio of from about 98:2 to 70:30.

1 . A process for deinking paper being recycled in a carbonate pulping procedure which is performed in the absence of hydroxides and peroxides comprising the addition of (a) at least one non-ionic alkoxylated alcohol surfactant deinking agent having a cloud point of about 55 to 85° C., and (b) at least two different fatty acid ink collectors: (i) at least one C16 to C20 fatty acid and (ii) at least one C22 to C30 fatty acid, wherein the ink collectors are used in a weight ratio of from about 98:2 to about 70:30.  
     
     
         2 . The process of  claim 1 , wherein the carbonate pulping procedure is performed at a pH of about 7.2 to about 8.5.  
     
     
         3 . The process of  claim 1 , wherein the carbonate pulping procedure is performed in an alkaline aqueous solution which comprises sodium silicate and sodium carbonate, with no sodium hydroxide.  
     
     
         4 . The process of  claim 1 , wherein the sodium silicate and sodium carbonate are used in a ratio between about 95 to 5 and about 50 to 50 by weight with respect to each other.  
     
     
         5 . The process of  claim 1 , wherein the cloud point of the surfactant is about 60 to 70° C.  
     
     
         6 . The process of  claim 1 , wherein the alkoxylated alcohol surfactant is an ethylene oxide/propylene oxide (EO/PO) alkoxylate of a C14 to C24 alcohol.  
     
     
         7 . The process of  claim 6 , wherein the alcohol is C18.  
     
     
         8 . The process of  claim 1 , wherein the saturated fatty acids have iodine values of less than 10.  
     
     
         9 . The process of  claim 1 , wherein the C16 to C20 fatty acid comprises stearic acid.  
     
     
         10 . The process of  claim 9 , wherein the stearic acid is added in the form of potassium stearate.  
     
     
         11 . The process of  claim 1 , wherein the C22 to C28 fatty acid comprises behenic acid.  
     
     
         12 . The process of  claim 11 , wherein the behenic acid is added in the form of potassium behenate.  
     
     
         13 . The process of  claim 1 , wherein the weight ratio of the C16 to C20 fatty acid ink collector to the C22 to C30 fatty acid ink collector is about 90:10.  
     
     
         14 . The process of  claim 1 , wherein the surfactant is added in an amount of about 0.05 to 0.5% by weight based upon the weight of the paper.  
     
     
         15 . The process of  claim 1 , wherein the fatty acid ink collectors are added in a total amount of about 0.05 to 0.75% by weight based upon the weight of the paper.