Wet strength and softness enhancement of paper products

Abstract

A method for making paper to enhance its wet strength includes adding separately to a cellulosic paper pulp furnish the following additives to form a treated pulp: a cationic wet strength resin whose cationic sites bond to anionic sites of cellulose fibers contained in the paper pulp furnish, and a hydrophobically modified anionic polyelectrolyte whose anionic sites bond with cationic sites of the cationic wet strength resin.

1 - 18 . (canceled)  
   
   
       19 . A paper product comprising: 
 a) at least one cellulosic component possessing anionic sites;    b) the reaction product of 
 i. cationic wet strength resin possessing cationic sites, and  
 ii. anionic polyelectrolyte possessing anionic sites and hydrophobic groups.  
   
   
   
       20 . The paper product of  claim 19  wherein the cationic wet strength resin has azetidinium or epoxide functionality.  
   
   
       21 . The paper product of  claim 20  wherein the cationic wet strength resin is a polymeric amine epichlorohydrin resin selected from the groups consisting of polyamide-epichlorohydrin resin, a polyalkylene polyamine-epichlorohydrin resin, polyamidoamine-epichlorohydrin resin and an amine polymer-epichlorohydrin resin.  
   
   
       22 . The paper product of  claim 19  wherein the anionic polyelectrolyte is made by reacting a polymeric compound having anhydride groups with an amine having the formula:  
       HNR 1 R 2    wherein R 1  and R 2  are each selected from the group consisting of hydrogen and a saturated or unsaturated, straight chain or branched aliphatic group having from 1 to 36 carbon atoms, with the proviso that at least one of R 1  and R 2  is a hydrophobic saturated or unsaturated, straight chain or branched aliphatic group having from about 8 to about 36 carbon atoms.    
   
   
       23 . The paper product of  claim 22  wherein the hydrophobic aliphatic group possesses from about 12 to about 24 carbon atoms.  
   
   
       24 . The paper product of  claim 22  wherein the amine is selected from the group consisting of octylamine, decylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine, nonadecylamine, eicosylamine, N-methyl-N-octylamine, N-methyl-N-decylamine, N-methyl-N-dodecylamine, N-methyl-N-tridecylamine, N-methyl-N-tetradecylamine, N-methyl-N-pentadecylamine, N-methyl-N-hexadecylamine, N-methyl-N-heptadecylamine, N-methyl-N-octadecylamine, N-methyl-N-nonadecylamine, N-methyl-N-eicosylamine, N-ethyl-N-octylamine, N-ethyl-N-decylamine, N-ethyl-N-dodecylamine, N-ethyl-N-tridecylamine, N-ethyl-N-tetradecylamine, N-ethyl-N-pentadecylamine, N-ethyl-N-hexadecylamine, N-ethyl-N-heptadecylamine, N-ethyl-N-octadecylamine, N-ethyl-N-nonadecylamine and N-ethyl-N-eicosylamine and mixtures thereof.  
   
   
       25 . The paper product of  claim 22  wherein the polymeric compound having anhydride groups is a copolymer of ethylene and maleic anhydride and the amine is octadecylamine or N-methyl-N-octadecylamine.  
   
   
       26 . The paper product of  claim 25  wherein the anionic polyelectrolyte includes from about 5 mole percent to about 10 mole percent octadecylamide or N-methyl-N-octadecylamide units.  
   
   
       27 . The paper product of  claim 22  wherein the anionic polyelectrolyte is made by reacting a polyolefin-co-maleic anhydride with the amine in a solvent to form an intermediate product, separating the intermediate product from the solvent and dissolving the intermediate product in an aqueous alkali solution to form a gel, and then treating the gel with an alkali halide solution.  
   
   
       28 . The paper product of  claim 19  wherein the anionic polyelectrolyte is made from a copolymer of an olefin and an unsaturated organic anhydride, wherein said olefin contains from about 8 to about 36 carbon atoms.  
   
   
       29 . The paper product of  claim 28  wherein the olefin is octadecene and the unsaturated organic anhydride is maleic acid.  
   
   
       30 . The paper product of  claim 19  wherein the cellulosic component is derived from kraft pulp.  
   
   
       31 . The paper product of  claim 19  wherein the anionic polyelectrolyte is combined with at least one non-substantive softener.  
   
   
       32 . The paper product of  claim 31  wherein the non-substantive softener is selected from the group consisting of fatty alcohol, fatty acid ester, fatty alcohol ester, alkoxylated fatty alcohol, esters of polyethylene glycol and/or polypropylene glycol with fatty acids, Guerbet alcohols and mixtures thereof.  
   
   
       33 . The paper product of  claim 32  wherein the alkoxylated fatty alcohol is an ethoxylated, propoxylated, or ethoxylated and propoxylated fatty alcohol and the fatty acid ester is a sorbitan fatty acid ester or a fatty acid ester of polyethylene glycol and/or polypropylene glycol.  
   
   
       34 . A hydrophobically modified anionic polyelectrolyte made by reacting a polymeric compound having anhydride groups with an amine having the formula:  
       HNR 1 R 2    wherein R 1  and R 2  are each selected from the group consisting of hydrogen and a saturated or unsaturated, straight chain or branched aliphatic group having from 1 to 36 carbon atoms, with the proviso that at least one of R 1  and R 2  is a hydrophobic saturated or unsaturated, straight chain or branched aliphatic group having from about 8 to about 36 carbon atoms.    
   
   
       35 . The hydrophobically modified polyelectrolyte of  claim 34  wherein the hydrophobic aliphatic group possesses from about 12 to about 24 carbon atoms.  
   
   
       36 . The hydrophobically modified anionic polyelectrolyte of  claim 34  wherein the amine is selected from the group consisting of octylamine, decylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine, nonadecylamine, eicosylamine, -methyl-N-octylamine, N-methyl-N-decylamine, N-methyl-N-dodecylamine, -methyl-N-tridecylamine, N-methyl-N-tetradecylamine, N-methyl-N-pentadecylamine, N-methyl-N-hexadecylamine, N-methyl-N-heptadecylamine, N-methyl-N-octadecylamine, N-methyl-N-nonadecylamine, N-methyl-N-eicosylamine, N-ethyl-N-octylamine, N-ethyl-N-decylamine, N-ethyl-N-dodecylamine, -ethyl-N-tridecylamine, N-ethyl-N-tetradecylamine, N-ethyl-N-pentadecylamine, N-ethyl-N-hexadecylamine, N-ethyl-N-heptadecylamine, N-ethyl-N-octadecylamine, N-ethyl-N-nonadecylamine and N-ethyl-N-eicosylamine and mixtures thereof.  
   
   
       37 . The hydrophobically modified polyelectrolyte of  claim 34  wherein said hydrophobically modified anionic polyelectrolyte includes from about 5 mole percent to about 10 mole percent octadecylamide or N-methyl-N-octadecylamide units.  
   
   
       38 . The hydrophobically modified polyelectrolyte of  claim 34  wherein the product of the reaction of the polymeric compound and the amine is further reacted with an alkali in aqueous solution.  
   
   
       39 . A hydrophobically modified anionic polyelectrolyte made by reacting a polymeric compound having anhydride groups and hydrophobic groups with an alkali in aqueous solution.  
   
   
       40 . The hydrophobically modified anionic polyelectrolyte of  claim 39  wherein the hydrophobic groups are saturated or unsaturated, straight chain or branched aliphatic groups each having from about 8 to about 36 carbon atoms.  
   
   
       41 . A composition for enhancing the wet strength of a cellulosic paper which comprises: 
 a) anionic polyelectrolyte possessing hydrophobic groups and anionic sites capable of bonding to unbound cationic sites in a cationic wet strength resin;    b) an alkali compound; and    c) water.    
   
   
       42 . The composition of  claim 41  wherein the anionic polyelectrolyte is made by reacting a polymeric compound having anhydride groups with an amine having the formula:  
       HNR 1 R 2    wherein R 1  and R 2  are each selected from the group consisting of hydrogen and a saturated or unsaturated, straight chain or branched aliphatic group having from 1 to 36 carbon atoms, with the proviso that at least one of R 1  and R 2  is a hydrophobic saturated or unsaturated, straight chain or branched aliphatic group having from about 8 to about 36 carbon atoms.    
   
   
       43 . The composition of  claim 42  wherein the hydrophobic aliphatic group possesses from about 12 to about 24 carbon atoms.  
   
   
       44 . The composition of  claim 42  wherein the amine is selected from the group consisting of octylamine, decylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine, nonadecylamine, eicosylamine, N-methyl-N-octylamine, N-methyl-N-decylamine, N-methyl-N-dodecylamine, N-methyl-N-tridecylamine, N-methyl-N-tetradecylamine, N-methyl-N-pentadecylamine, N-methyl-N-hexadecylamine, N-methyl-N-heptadecylamine, N-methyl-N-octadecylamine, N-methyl-N-nonadecylamine, N-methyl-N-eicosylamine, N-ethyl-N-octylamine, N-ethyl-N-decylamine, N-ethyl-N-dodecylamine, -ethyl-N-tridecylamine, N-ethyl-N-tetradecylamine, N-ethyl-N-pentadecylamine, N-ethyl-N-hexadecylamine, N-ethyl-N-heptadecylamine, N-ethyl-N-octadecylamine, N-ethyl-N-nonadecylamine and N-ethyl-N-eicosylamine and mixtures thereof.  
   
   
       45 . The composition of  claim 42  wherein the polymeric compound having anhydride groups is a copolymer of ethylene and maleic anhydride and the amine is octadecylamine or N-methyl-N-octadecylamine.  
   
   
       46 . The composition of  claim 45  wherein the anionic polyelectrolyte includes from about 5 mole percent to about 10 mole percent octadecylamide or N-methyl-N-octadecylamide units.  
   
   
       47 . The composition of  claim 38  wherein the anionic polyelectrolyte is made from a copolymer of an olefin and an unsaturated organic anhydride, wherein said olefin contains from about 8 to about 36 carbon atoms.  
   
   
       48 . The composition of  claim 44  wherein the olefin is octadecene and the unsaturated organic anhydride is maleic acid.  
   
   
       49 . The composition of  claim 41  further including an alkali metal halide salt.  
   
   
       50 . The composition of  claim 49  wherein the alkali compound is sodium hydroxide and the alkali metal salt is sodium chloride.  
   
   
       51 . The composition of  claim 41  further including a non-substantive softener.  
   
   
       52 . The composition of  claim 51  wherein the non-substantive softener is selected from the group consisting of fatty alcohol, fatty acid ester, fatty alcohol ester, alkoxylated fatty alcohol, esters of polyethylene glycol and/or polypropylene glycol with fatty acids, Guerbet alcohols and mixtures thereof.  
   
   
       53 . The composition of  claim 52  wherein the alkoxylated fatty alcohol is an ethoxylated, propoxylated, or ethoxylated and propoxylated fatty alcohol and the fatty acid ester is a sorbitan fatty acid ester or a fatty acid ester of polyethylene glycol and/or polypropylene glycol.  
   
   
       54 . A composition for enhancing the wet strength of a cellulosic paper which comprises: 
 a) anionic polyelectrolyte possessing hydrophobic groups and anionic sites capable of bonding to unbound cationic sites in a cationic wet strength resin;    b) an aqueous solution of an alkali compound and alkali halide salt; and    c) a Guerbet alcohol.    
   
   
       55 . The composition of  claim 54  wherein the anionic polyelectrolyte is made by reacting a polymeric compound having anhydride groups with an amine having the formula:  
       HNR 1 R 2    wherein R 1  and R 2  are each selected from the group consisting of hydrogen and a saturated or unsaturated, straight chain or branched aliphatic group having from 1 to 36 carbon atoms, with the proviso that at least one of R 1  and R 2  is a hydrophobic saturated or unsaturated, straight chain or branched aliphatic group having from about 8 to about 36 carbon atoms.    
   
   
       56 . The composition of  claim 54  wherein the anionic polyelectrolyte is made from a copolymer of an olefin and an unsaturated organic anhydride, wherein said olefin contains from about 8 to about 36 carbon atoms.