Method of brightness enhancement

Abstract

A method of enhancing brightness of paper made from mechanical pulps or recycled pulps that comprise: adding an effective amount of one or more chelants and one or more surfactants to a bleaching stage of a papermaking process that involves the addition of hydrosulfite is disclosed.

1 . A method of enhancing brightness of paper made from mechanical pulps that comprise: adding an effective amount of one or more chelants and one or more surfactants to a bleaching stage of a papermaking process that involves the addition of hydrosulfite.  
   
   
       2 . The method of  claim 1 , wherein said chelants and surfactants are added as a mixture or sequentially.  
   
   
       3 . The method of  claim 1 , wherein said chelants are selected from the group consisting of: aminophosphonates, aminophosphates, DTMPA, AMP, DTMPA-polyacrylate, aminocarboxylates, EDTA, and DTPA.  
   
   
       4 . The method of  claim 1 , wherein said surfactants are non-ionic surfactants selected from the group of consisting of: polyalkoxylated long-chain alcohols; ethoxylated alcohols; and propoxylated alcohols.  
   
   
       5 . The method of  claim 1 , wherein said chelants are added to said papermaking process at a dose of 0.01 to 10 lbs/ton of o.d. pulp, preferably 1 to 4 lbs/ton of o.d. pulp.  
   
   
       6 . The method of  claim 1 , wherein said surfactants are added to said papermaking process at a dose of 0.01 to 10 lbs/ton of o.d. pulp, preferably 0.5 to 2 lb/ton of o.d. pulp.  
   
   
       7 . A method of enhancing brightness of paper made from recycled pulps that comprises the step of: adding an effective amount of one or more chelants and one or more surfactants to a bleaching stage of a papermaking process that involves the addition of hydrosulfite.  
   
   
       8 . The method of  claim 7 , wherein said chelants and surfactants are added as a mixture or sequentially.  
   
   
       9 . The method of  claim 7 , wherein said chelants are selected from the group consisting of: aminophosphonates, aminophosphates, DTMPA, AMP, DTMPA-polyacrylate, aminocarboxylates, EDTA, and DTPA.  
   
   
       10 . The method of  claim 7 , wherein said surfactants are non-ionic surfactants selected from the group of non-ionic surfactants consisting of: polyalkoxylated long-chain alcohols; ethoxylated alcohols; and propoxylated alcohols.  
   
   
       11 . The method of  claim 7 , wherein said chelants are added to said papermaking process at a dose of 0.01 to 10 lbs/ton of o.d. pulp, preferably 1 to 4 lbs/ton of o.d. pulp.  
   
   
       12 . The method of  claim 7 , wherein said surfactants are added to said papermaking process at a dose of 0.01 to 10 lbs/ton of o.d. pulp, preferably 0.5 to 2 lb/ton of o.d. pulp.  
   
   
       13 . The method of  claim 2 , wherein said chelants and surfactants are added as a single product comprising of 15% pentasodium DTPA, 3% etoxylated, propoxylated hexadecanol and 17% sodium xylenesulfonate at pH about 7.  
   
   
       14 . The method of  claim 2 , wherein said chelants and surfactants are added as separate products, one chelant comprising of 29% pentasodium DTMPA and 14% sodium polyacrylate at pH about 6 and one surfactant comprising of 16% ethoxylated, propoxylated hexadecanol at pH about 8.  
   
   
       15 . The method of  claim 7 , wherein said chelants and surfactants are added as a single product comprising of 15% pentasodium DTPA, 3% etoxylated, propoxylated hexadecanol and 17% sodium xylenesulfonate at pH about 7.  
   
   
       16 . The method of  claim 7 , wherein said chelants and surfactants are added as separate products, one chelant comprising of 29% pentasodium DTMPA and 14% sodium polyacrylate at pH about 6 and one surfactant comprising of 16% ethoxylated, propoxylated hexadecanol at pH about 8.  
   
   
       17 . The method of  claim 1 , wherein said surfactants are selected from the group consisting of: anionic; long-chain carboxylic acids; alkylarylsulfonates; alkylsulfates; alkylsulfonates; arylsulfonates; cationic; tertiary alkylammonium; alkylpyridinium salts; ampholitic species; alkylaminoacids; non-ionic; oxyalkylated alcohols; polyethyleneglycol esters of fatty acids; oxyalkylated; and andalkylphenols.  
   
   
       18 . The method of  claim 7 , wherein said surfactants are selected from the group consisting of: anionic; long-chain carboxylic acids; alkylarylsulfonates; alkylsulfates; alkylsulfonates; arylsulfonates; cationic; tertiary alkylammonium; alkylpyridinium salts; ampholitic species; alkylaminoacids; non-ionic; oxyalkylated alcohols; polyethyleneglycol esters of fatty acids; oxyalkylated; and andalkylphenols.