Glyoxalation of vinylamide polymer
The present invention is directed to a method for preparing a cellulose reactive adduct of polyvinylamide and a composition resulting from the method. The preparation of the cellulose reactive adduct is carried out close to a Critical Concentration defined herein. When the reaction is run close to this Critical Concentration, the risk of gelation is minimized, consumed glyoxal is maximized, and shelf live is enhanced. Additionally, the glyoxalated vinylamides of the present invention impart improved wet and dry strengthening efficiency to paper and paperboard when compared to adducts disclosed in previously described art.
1. A method for preparing a cellulose reactive functionalized polyvinylamide adduct comprising
reacting a substantially aqueous reaction mixture of a vinylamide polymer and a cellulose reactive agent to form the adduct,
wherein the concentration of the vinylamide polymer is below, equal to or no more than 1% above a Critical Concentration and the Critical Concentration is defined as the concentration of the vinylamide polymer above which Critical Concentration the viscosity increases for the reaction mixture resulting from the forward progress of the adduct formation, and below which Critical Concentration, the viscosity decreases for the reaction mixture resulting from the forward progress of adduct formation, wherein the cellulose reactive functionalized polyvinylamide adduct is characterized by a viscosity of no more than 30 centipoise measured using a BROOKFIELD viscometer at a speed of 60 rpm and a temperature of 25° C.
2. A water-soluble glyoxalated-polyvinylamide thermosetting resin obtained by the method according to claim 1 .
3. The method according to claim 1 wherein the cellulose reactive agent comprises more than one aldehyde functionality.
4. The method according to claim 1 , wherein the cellulose reactive agent is glyoxal, glutaraldehyde, furan dialdehyde, 2-hydroxyadipaldehyde, succinaldehyde, dialdehyde starch, diepoxy compounds, and combinations thereof.
5. The method according to claim 1 wherein the vinylamide polymer is a homopolymer or copolymer formed from (meth)acrylamide or a substituted (meth)acrylamide.
6. A method according to claim 1 wherein the vinylamide polymer is nonionic, cationic, potentially cationic, anionic, potentially anionic and/or amphoteric.
7. The method according to claim 6 , wherein the vinylamide polymer is cationic and formed from (meth)acrylamide or a substituted (meth)acrylamide and a cationic monomer, which cationic monomer is selected from the group consisting of diallyldialkyl ammonium salts, (dialkylamino)alkyl (meth)acrylates acid addition or quaternary salts, 2-vinylpyridines acid addition or quaternary salts, dialkylamino alkyl(meth)acrylamides acid addition or quaternary salts, (p-vinylphenyl)-trimethylammonium chloride and 1-methacryloyl-4-methyl piperazine acid addition or quaternary ammonium salts.
8. The method according to claim 7 , wherein the vinylamide polymer is formed from about 20 to about 99 weight percent of the (meth)acrylamide or a substituted (meth)acrylamide monomer.
9. The method according to claim 1 wherein the vinylamide polymer or the polyvinylamide adduct is linear, crosslinked, chain-transferred, or crosslinked and chain-transferred.
10. The method according to claim 9 , wherein the vinylamide polymer or the polyvinylamide adduct is crosslinked using at least a difunctional monomer selected from group consisting of methylene bis(meth)acrylamide; triallylammonium chloride; tetraallyl ammonium chloride; polyethyleneglycol diacrylate; polyethyleneglycol dimethacrylate; N-vinyl acrylamide; divinylbenzene; tetra(ethyleneglycol) diacrylate; dimethylallylaminoethylacrylate ammonium chloride; diallyloxyacetic acid; Na salt; diallyloctylamide; trimethyllpropane ethoxylate triacryalte; N-allylacrylamide; N-methylallylacrylamide; pentaerythritol triacrylate and combinations thereof.
11. The method according to claim 1 wherein the vinylamide is partially hydrolysed or partially converted to a Mannich base.
12. The method according to claim 1 wherein the vinylamide polymer is a copolymer of (meth)acrylamide and diallyldimethylammonium halide.
13. The method according to claim 1 wherein the glyoxal may be added before the reaction is catalyzed or added as two or more separate additions before, during, or after the catalyzed reaction.
14. The method according to claim 1 wherein the reaction is run continuously or in batch mode.
15. The method according to claim 1 wherein the average molecular weight of the vinylamide polymer is from 500 to about 5,000,000.
16. The method according to claim 1 wherein adduct formation is determined by measuring a change in turbidity or viscosity of the aqueous reaction and the change in turbidity or viscosity is the difference in turbidity or viscosity of the aqueous reaction at the start of the reaction and a predetermined endpoint.
17. The method according to claim 1 wherein the vinylamide concentration is less than about 4 weight percent of the total reaction mixture, and the weight average molecular weight of the starting vinylamide polymer is between 1,000 and 30,000.
18. The method according to claim 1 , wherein the non-gelled cellulose reactive functionalized polyvinylamide adduct is characterized by a turbidity of 2 to 1005 NTU (nephelometric units).
19. The method according to claim 1 , wherein the vinylamide polymer has an average molecular weight of at least about 30,000 to about 500,000.