Additive compositions for papermaking

Abstract

A drainage-optimized additive composition for papermaking is disclosed. The composition comprises an aqueous media, a glyoxalated polyacrylamide (GPAM) resin, and an anionic polyacrylamide (APAM) resin. The GPAM resin has a weight average molecular weight (Mw) of at least about 5 MDa and a cationic monomer content of at least about 4 mol %. The APAM resin has a Mw of at least about 0.25 MDa, and an anionic monomer content up to about 25 mol %. A method of preparing the additive composition is also disclosed, and comprises preparing a cationic acrylamide (CPAM) prepolymer having a predetermined cationic monomer, selectively glyoxalating the CPAM prepolymer in aqueous media during glyoxalation to give the GPAM resin, and combining the GPAM and APAM resins. The method may be carried out in situ during a papermaking process (i.e., as an on-site method), and may be implemented in different forms during the process of forming paper.

1 . A drainage-optimized additive composition for papermaking, comprising:
 an aqueous media;   a glyoxalated polyacrylamide (GPAM) resin having a weight average molecular weight (Mw) of at least about 5 MDa and a cationic monomer content of at least about 4 mol %; and   an anionic polyacrylamide (APAM) resin having a weight average molecular weight (Mw) of at least about 0.25 MDa and an anionic monomer content of up to about 25 mol %,   wherein the APAM resin and the GPAM resin are utilized in a wt/wt ratio of from about 1:99 to about 1:2 (APAM:GPAM), based on the total weight of the APAM resin and the GPAM resin.   
     
     
         2 . The additive composition of  claim 1 , wherein the glyoxalated polyacrylamide GPAM resin comprises the reaction product of (A) a cationic acrylamide (CPAM) prepolymer and (B) glyoxal in an aqueous media, and wherein the CPAM prepolymer (A) and the glyoxal (B) are reacted in a dry weight (w/w) ratio of from about 85:30 to about 95:5 (A):(B). 
     
     
         3 . The additive composition of  claim 1 , wherein the CPAM prepolymer (A) comprises the reaction product of:
 (A1) an acrylamide (AM) monomer;   (A2) a cationic monomer; and   (A3) optionally, one or more additional ethylenically unsaturated monomer(s); and wherein the CPAM prepolymer (A) comprises at least about 10 mol % of cationic monomer units derived from the cationic monomer (A2).   
     
     
         4 . The additive composition of  claim 3 , wherein the AM monomer (A1), the cationic monomer (A2), and optionally the additional ethylenically unsaturated monomer(s) (A3) are reacted in the presence of a chain transfer agent. 
     
     
         5 . The additive composition of  claim 3 , wherein:
 (i) the AM monomer (A1) comprises acrylamide;   (ii) the cationic monomer (A2) comprises diallyldimethylammonium chloride (DADMAC);   (iii) the one or more additional ethylenically unsaturated monomer(s) (A3), when present, are selected from styrenes, alkyl acrylates, and vinyl acetates; or   (iv) any combination of (i)-(iii).   
     
     
         6 . The additive composition of  claim 1 , wherein the glyoxalated polyacrylamide (GPAM) resin comprises:
 (i) a weight average molecular weight (Mw) of at least about 6 MDa;   (ii) a cationic monomer content of at least about 12 mol %; or   (iii) both (i) and (ii).   
     
     
         7 . The additive composition of  claim 1 , wherein the anionic polyacrylamide (APAM) resin comprises:
 (i) a weight average molecular weight (Mw) of at least about 0.5 MDa;   (ii) an anionic monomer content of less than about 20 mol %; or   (iii) both (i) and (ii).   
     
     
         8 . The additive composition of  claim 1 , wherein the additive composition is optimized for drainage performance by selecting the relative proportion of the APAM resin and the GPAM resin utilized based on:
 (i) the weight average molecular weight (Mw) of the glyoxalated polyacrylamide (GPAM) resin;   (ii) the cationic monomer content of the glyoxalated polyacrylamide (GPAM) resin;   (iii) the weight average molecular weight (Mw) of the anionic polyacrylamide (APAM) resin;   (iv) the anionic monomer content of the anionic polyacrylamide (APAM) resin; or   (v) any combination of (i)-(iv),   such that the additive composition exhibits a drainage performance greater than that of the APAM resin used alone, and substantially no less than the drainage performance exhibited without the use of either of the APAM resin and the GPAM resin, as determined under substantially the same conditions via vacuum drainage test performed after application to a cellulosic pulp suspension.   
     
     
         9 . A method of preparing a drainage-optimized additive composition for papermaking, comprising:
 preparing in an aqueous media a glyoxalated polyacrylamide (GPAM) resin having a weight average molecular weight (Mw) of at least about 5 MDa and a cationic monomer content of at least about 4 mol %;   providing an anionic polyacrylamide (APAM) resin having a weight average molecular weight (Mw) of at least about 0.25 MDa and an anionic monomer content of up to about 25 mol %; and   combining the anionic polyacrylamide (APAM) resin and the glyoxalated polyacrylamide (GPAM) resin in a wt/wt ratio of from about 1:20 to about 1:5 (APAM:GPAM), based on the total weight of the APAM resin and the GPAM resin, thereby giving the additive composition.   
     
     
         10 . The method of  claim 9 , wherein preparing the glyoxalated polyacrylamide (GPAM) resin comprises selectively glyoxalating a cationic acrylamide (CPAM) prepolymer with glyoxal by reacting the CPAM prepolymer (A) and the glyoxal (B):
 (i) in a dry weight (w/w) ratio of from about 85:30 to about 95:5 (A):(B);   (ii) in a low-solids glyoxalation process with a solids content less than about 5%; or   (iii) both (i) and (ii).   
     
     
         11 . The method of  claim 10 , further comprising preparing the CPAM prepolymer (A), wherein preparing the CPAM prepolymer (A) comprises reacting (A1) an acrylamide (AM) monomer, (A2) a cationic monomer, and optionally (A3) one or more additional ethylenically unsaturated monomer(s) in the presence of a chain transfer agent. 
     
     
         12 . The method of  claim 11 , wherein:
 (i) the AM monomer (A1) comprises acrylamide;   (ii) the cationic monomer (A2) comprises diallyldimethylammonium chloride (DADMAC);   (iii) the one or more additional ethylenically unsaturated monomer(s) (A3), when present, are selected from styrenes, alkyl acrylates, and vinyl acetates; or   (iv) any combination of (i)-(iii).   
     
     
         13 . The method of  claim 9 , further comprising applying the anionic polyacrylamide (APAM) resin to in an aqueous suspension of cellulosic fibers, wherein combining the anionic polyacrylamide (APAM) resin and the glyoxalated polyacrylamide (GPAM) resin comprising providing the glyoxalated polyacrylamide (GPAM) resin to the aqueous suspension of cellulosic fibers after the anionic polyacrylamide (APAM) resin is applied thereto. 
     
     
         14 . The method of  claim 9 , wherein the glyoxalated polyacrylamide (GPAM) resin is prepared in-situ in an aqueous suspension of cellulosic fibers comprising the anionic polyacrylamide (APAM) resin. 
     
     
         15 . A process of forming paper, said process comprising:
 (1) providing an aqueous suspension of cellulosic fibers;   (2) combining an additive composition comprising an anionic polyacrylamide (APAM) resin and a glyoxalated polyacrylamide (GPAM) resin prepared in-situ with the aqueous suspension, wherein the additive composition is the additive composition of  claim 1 ;   (3) forming the cellulosic fibers into a sheet; and   (4) drying the sheet to produce a paper.   
     
     
         16 . The process of  claim 15 , wherein combining the additive composition with the aqueous suspension comprises first providing the anionic polyacrylamide (APAM) resin to the aqueous suspension, and then providing the glyoxalated polyacrylamide (GPAM) resin to the aqueous suspension. 
     
     
         17 . A process of forming paper, said process comprising:
 (1) providing an aqueous suspension of cellulosic fibers;   (2) forming the cellulosic fibers into a sheet;   (3) applying an additive composition comprising an anionic polyacrylamide (APAM) resin and a glyoxalated polyacrylamide (GPAM) resin to a surface of the sheet, wherein the additive composition is the additive composition of  claim 1 ; and   (4) drying the sheet to produce a paper.   
     
     
         18 . The process of  claim 17 , wherein the applying the additive composition to the surface of the sheet comprises:
 (i) sequentially applying the anionic polyacrylamide (APAM) resin and then the glyoxalated polyacrylamide (GPAM) resin;   (ii) sequentially applying the glyoxalated polyacrylamide (GPAM) resin and then the anionic polyacrylamide (APAM) resin; or   (iii) applying the glyoxalated polyacrylamide (GPAM) resin and the anionic polyacrylamide (APAM) resin at substantially the same time.   
     
     
         19 . The process of  claim 17 , wherein:
 (i) a drainage rate exhibited during forming the cellulosic fibers into the sheet and/or drying the sheet to produce the paper is reduced by at least about 10%, compared to a drainage rate of a substantially similar process that is substantially free from the additive composition;   (ii) the paper exhibits a ring crush performance (TAPPI T822) that is increased by at least about 1%, compared to a performance of a paper prepared with a substantially similar process that is substantially free from the additive composition; or   (iii) both (i) and (ii).   
     
     
         20 . The process of  claim 19 , wherein the drainage rate exhibited during forming the cellulosic fibers into the sheet and/or drying the sheet to produce the paper is:
 (i) within about 15% of a drainage rate of a substantially similar process that is substantially free from the anionic polyacrylamide (APAM) resin in the additive composition;   (ii) reduced by at least about 15%, compared to a drainage rate of a substantially similar process that is substantially free from the glyoxalated polyacrylamide (GPAM) resin of the additive composition; or   (iii) both (i) and (ii).