Method for reducing deposits in the drying section in the manufacture of paper, paperboard, and cardboard

Abstract

A process for reducing deposits in the dry section in the production of paper, board and cardboard by adding (a) at least one water-soluble cationic polymer and (b) at least one aqueous dispersion of a polymer size to a paper stock, draining the paper stock with sheet formation and drying the paper products.

1 . A process for producing a paper products product with reduced deposits, the process comprising:
 adding a water-soluble cationic polymer (a) and an aqueous dispersion of a polymer size (b) to a paper stock,   draining the paper stock, to obtain a sheet, and   drying the sheet, to obtain a paper product.   
     
     
         2 . The process of  claim 1 , wherein the polymer (a) is at least one selected from the group consisting of a polymer comprising a vinylamine unit, a cationic homo-polymer comprising (meth)acrylamide, a cationic copolymer comprising (meth)acrylamide, a polyallylamine, a polyaminoalkyl vinyl ether, a polymer obtained by a process comprising reacting a polyamidoamine compound with epihalohydrin, a polymer obtained by a process comprising reacting a polyamine compound with epihalohydrin, an amphoteric polymer having an overall cationic charge, a polymer comprising an ethyleneimine unit and a homopolymer comprising a cationic or protonatable group. 
     
     
         3 . The process of  claim 2 , wherein the polymer (a) is a polymer comprising a vinylamine unit obtained by at least one process selected from the group consisting of:
 (i) polymerizing a monomer of formula (I)   
       
         
           
           
               
               
           
         
         wherein R 1 , R 2  are H or C 1 - to C 6 -alkyl, to obtain an initial polymer; and subsequently 
         eliminating, partially or completely, the CO—R 1  groups comprised, in polymerized form, in the initial polymer forming amino groups, and 
         (ii) degrading, by Hofmann degradation, a polymer comprising at least one selected from the group consisting of an acrylamide and a methacrylamide unit. 
       
     
     
         4 . The process of  claim 2 , wherein the polymer (a) is at least one polymer comprising an ethyleneimine unit selected from the group consisting of:
 a homopolymer of ethyleneimine;   a polymer obtained by a process comprising reacting a polyethyleneimine with an at least bifunctional crosslinking agent;   a polymer obtained by a process comprising reacting a polyamidoamine grafted with ethyleneimine with an at least bifunctional crosslinking agent;   an amidated polyethyleneimine obtained by a process comprising reacting a polyethyleneimine with a monobasic carboxylic acid,   a Michael adduct obtained by a process comprising reacting a polyethyleneimine with an ethylenically unsaturated acid, salt, ester, an amide, or a nitrile of a monoethylenically unsaturated carboxylic acid;   a phosphonomethylated polyethyleneimine,   a carboxylated polyethyleneimine; and   an alkoxylated polyethyleneimine.   
     
     
         5 . The process of  claim 1 , wherein the aqueous dispersion (b) is a finely divided, cationic or amphoteric, aqueous polymer dispersion obtained by a process comprising:
 a first polymerizing of monomers, to obtain a prepolymer; and then   a second polymerizing, by emulsion polymerization, of the prepolymer,   wherein the second polymerizing is carried out in an aqueous solution and in the presence of ethylenically unsaturated monomers.   
     
     
         6 . The process of  claim 4 , wherein the first polymerizing is by solution polymerization and the monomers comprise:
 (i) a nitrogen-comprising monomer which carry comprising at least one selected from the group consisting of an amino group and a quaternary ammonium group,   (ii) a nonionic, hydrophobic, ethylenically unsaturated monomer,   (iii) optionally, an ethylenically unsaturated monomer comprising an acid group; and   (iv) optionally, a nonionic, hydrophilic, ethylenically unsaturated monomer, and   wherein the ethylenically unsaturated monomers, in the second polymerizing, comprise a monomer mixture comprising nonionic, hydrophobic, ethylenically unsaturated monomers.   
     
     
         7 . The process of  claim 1 , wherein, during the adding, the polymer (a) and the aqueous dispersion (b) are added to the paper stock in any desired sequence or as a mixture. 
     
     
         8 . The process of  claim 1 , wherein the adding comprises:
 adding the polymer (a) to the paper stock; and then   adding the aqueous dispersion (b) to the paper stock.   
     
     
         9 . The process of  claim 1 , wherein, during the adding, the aqueous dispersion (b) and the polymer (a) are simultaneously added to the paper stock. 
     
     
         10 . The process of  claim 1 , wherein the adding comprises:
 adding the aqueous dispersion (b) to the paper stock; and then   adding, by metering in, the polymer (a) to the paper stock.   
     
     
         11 . The process of  claim 1 , wherein the polymer (a) is a cationic homo-polymer comprising (meth)acrylamide. 
     
     
         12 . The process of  claim 1 , wherein the polymer (a) is a cationic copolymer comprising (meth)acrylamide. 
     
     
         13 . The process of  claim 1 , wherein the polymer (a) is a polyallylamine. 
     
     
         14 . The process of  claim 1 , wherein the polymer (a) is a polyaminoalkyl vinyl ether. 
     
     
         15 . The process of  claim 1 , wherein the polymer (a) is obtained by a process comprising reacting a polyamidoamine compound with epihalohydrin. 
     
     
         16 . The process of  claim 1 , wherein the polymer (a) is obtained by a process comprising reacting a polyamine compound with epihalohydrin. 
     
     
         17 . The process of  claim 1 , wherein the polymer (a) is an amphoteric polymer having an overall cationic charge. 
     
     
         18 . The process of  claim 1 , wherein the polymer (a) is a polymer comprising an ethyleneimine unit. 
     
     
         19 . The process of  claim 1 , wherein the polymer (a) is a homopolymer comprising a cationic or protonatable group. 
     
     
         20 . The process of  claim 1 , wherein the paper products are at least one selected from the group consisting of paper, board, and cardboard.