Patent Application
20240417929
The present disclosure generally relates to papermaking. More particularly, the disclosure relates to compositions and methods used to increase paper strength.
In most papermaking processes, a thick cellulosic fiber suspension is diluted with white water and transferred to a headbox. The headbox distributes the suspension onto a moving screen, wherein the liquid component is drained through the screen and the fiber forms a wet web on the screen. The wet web may be transported to a press section and then to a dryer.
Chemical additives are added at various points of the papermaking process for various reasons. For example, certain chemicals may be added to assist with drainage of the liquid component of the cellulosic fiber suspension. Further, strength aids may be added to increase the tensile strength properties of a paper sheet produced from the process. However, the additives must be carefully chosen such that they do not interfere with or otherwise degrade the effectiveness of other additives present in the resulting paper product.
The present disclosure provides methods and compositions for improving a papermaking process. In some embodiments disclosed herein, a method of improving a papermaking process includes adding a strength aid to a cellulosic fiber suspension in the papermaking process and adding a dewatering agent to the cellulosic fiber suspension. The dewatering agent may comprise a polymer having a reduced specific viscosity from about 2.5 to about 5.5 dL/g.
The present disclosure also provides a composition for improving a papermaking process. The composition comprises a strength aid and a dewatering agent, wherein the dewatering agent comprises a polymer having a reduced specific viscosity from about 2.5 to about 5.5 dL/g.
The foregoing has outlined rather broadly the features and technical advantages of the present disclosure in order that the detailed description that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter that form the subject of the claims of this application.
A detailed description of the invention is hereafter described with specific reference being made to the drawings in which:
Various embodiments are described below with reference to the drawings in which like elements generally are referred to by like numerals. The relationship and functioning of the various elements of the embodiments may better be understood by reference to the following detailed description. However, embodiments are not strictly limited to those illustrated in the drawings or described below.
Examples of methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used in practice or testing of the present disclosure. All publications, patent applications, patents and other reference materials mentioned herein are incorporated by reference in their entirety. The materials, methods, and examples disclosed herein are illustrative only and not intended to be limiting.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present document, including definitions, will control.
Unless otherwise indicated, an alkyl group as described herein alone or as part of another group is an optionally substituted linear or branched saturated monovalent hydrocarbon substituent containing from, for example, one to about sixty carbon atoms, such as one to about thirty carbon atoms, in the main chain. Examples of unsubstituted alkyl groups include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, i-pentyl, s-pentyl, t-pentyl, and the like.
The terms “aryl” or “ar” as used herein alone or as part of another group (e.g., arylene) denote optionally substituted homocyclic aromatic groups, such as monocyclic or bicyclic groups containing from about 6 to about 12 carbons in the ring portion, such as phenyl, biphenyl, naphthyl, substituted phenyl, substituted biphenyl or substituted naphthyl. The term “aryl” also includes heteroaryl functional groups. It is understood that the term “aryl” applies to cyclic substituents that are planar and comprise 4n+2 electrons, according to Huckel's Rule.
“Cycloalkyl” refers to a cyclic alkyl substituent containing from, for example, about 3 to about 8 carbon atoms, preferably from about 4 to about 7 carbon atoms, and more preferably from about 4 to about 6 carbon atoms. Examples of such substituents include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and the like. The cyclic alkyl groups may be unsubstituted or further substituted with alkyl groups, such as methyl groups, ethyl groups, and the like.
“Heteroaryl” refers to a monocyclic or bicyclic 5- or 6-membered ring system, wherein the heteroaryl group is unsaturated and satisfies Huckel's rule. Non-limiting examples of heteroaryl groups include furanyl, thiophenyl, pyrrolyl, pyrazolyl, imidazolyl, 1,2,3-triazolyl, 1,2,4-triazolyl, isoxazolyl, oxazolyl, isothiazolyl, thiazolyl, 1,3,4-oxadiazol-2-yl, 1,2,4-oxadiazol-2-yl, 5-methyl-1,3,4-oxadiazole, 3-methyl-1,2,4-oxadiazole, pyridinyl, pyrimidinyl, pyrazinyl, triazinyl, benzofuranyl, benzothiophenyl, indolyl, quinolinyl, isoquinolinyl, benzimidazolyl, benzoxazolinyl, benzothiazolinyl, quinazolinyl, and the like.
Compounds of the present disclosure may be substituted with suitable substituents. The term “suitable substituent,” as used herein, is intended to mean a chemically acceptable functional group, preferably a moiety that does not negate the activity of the compounds. Such suitable substituents include, but are not limited to, halo groups, perfluoroalkyl groups, perfluoro-alkoxy groups, alkyl groups, alkenyl groups, alkynyl groups, hydroxy groups, oxo groups, mercapto groups, alkylthio groups, alkoxy groups, aryl or heteroaryl groups, aryloxy or heteroaryloxy groups, aralkyl or heteroaralkyl groups, aralkoxy or heteroaralkoxy groups, HO—(C═O)— groups, heterocylic groups, cycloalkyl groups, amino groups, alkyl- and dialkylamino groups, carbamoyl groups, alkylcarbonyl groups, alkoxycarbonyl groups, alkylaminocarbonyl groups, dialkylamino carbonyl groups, arylcarbonyl groups, aryloxy-carbonyl groups, alkylsulfonyl groups, and arylsulfonyl groups. In some embodiments, suitable substituents may include halogen, an unsubstituted C1-C12 alkyl group, an unsubstituted C4-C6 aryl group, or an unsubstituted C1-C10 alkoxy group. Those skilled in the art will appreciate that many substituents can be substituted by additional substituents.
The term “substituted” as in “substituted alkyl,” means that in the group in question (i.e., the alkyl group), at least one hydrogen atom bound to a carbon atom is replaced with one or more substituent groups, such as hydroxy (—OH), alkylthio, phosphino, amido (—CON(RA)(RB), wherein RA and RB are independently hydrogen, alkyl, or aryl), amino(—N(RA)(RB), wherein RA and RB are independently hydrogen, alkyl, or aryl), halo (fluoro, chloro, bromo, or iodo), silyl, nitro (—NO2), an ether (—ORA wherein RA is alkyl or aryl), an ester (—OC(O)RA wherein RA is alkyl or aryl), keto (—C(O)RA wherein RA is alkyl or aryl), heterocyclo, and the like.
When the term “substituted” introduces a list of possible substituted groups, it is intended that the term apply to every member of that group. That is, the phrase “optionally substituted alkyl or aryl” is to be interpreted as “optionally substituted alkyl or optionally substituted aryl.”
The terms “polymer,” “copolymer,” “polymerize,” “copolymerize,” and the like include not only polymers comprising two monomer residues and polymerization of two different monomers together, but also include (co)polymers comprising more than two monomer residues and polymerizing together more than two or more other monomers. For example, a polymer as disclosed herein includes a terpolymer, a tetrapolymer, polymers comprising more than four different monomers, as well as polymers comprising, consisting of, or consisting essentially of two different monomer residues. Additionally, a “polymer” as disclosed herein may also include a homopolymer, which is a polymer comprising a single type of monomer unit.
Unless specified differently, the polymers of the present disclosure may be linear, branched, crosslinked, structured, synthetic, semi-synthetic, natural, and/or functionally modified. A polymer of the present disclosure can be in the form of a solution, a dry powder, a liquid, or a dispersion, for example.
The term “cellulosic fiber suspension” means a mixture comprising a liquid medium, such as water, within which solids, such as fibers (for example cellulose fibers) and optionally fillers, are dispersed or suspended such that between about >99% to about 45% by mass of the suspension is liquid medium. The portion of the papermaking process prior to the press section where a liquid medium, such as water, comprises more than about 45% of the mass of the substrate is referred to as the “wet end.” Conversely, the term “dry end” refers to that portion of the papermaking process including and subsequent to the press section where a liquid medium, such as water, typically comprises less than about 45% of the mass of the substrate.
The cellulosic fiber suspension, and thus a sheet formed from the suspension, may comprise, for example, a natural fiber, a synthetic fiber, a chemical pulp, a mechanical pulp, a vegetable fiber, a recycled fiber, a filler, or any combination thereof.
The paper manufacturing process can be organized into different general sections. For example, one section, often referred to as the “wet end,” includes the location where a cellulosic fiber suspension is disposed as a thin layer on a moving papermaking wire or forming fabric. Another section is commonly referred to as the “press section,” which is where the thin layer is pressed to remove additional water. Following that is the dryer section where the pressed layer moves through a series of heated rollers. At this point, the dry substrate can be rewetted by passing it through a size press and further dried by passing it through another set of heated rollers. Finally, the dried substrate passes through a paper finishing section, such as a calendaring section (see, for example, Handbook for Pulp and Paper Technologists, 3rd Edition, by Gary A. Smook, Angus Wilde Publications Inc., (2002) and The Nalco Water Handbook (3rd Edition), by Daniel Flynn, McGraw Hill (2009)).
In some aspects of the present disclosure, the compounds, components, compositions and/or methods disclosed herein may be employed in the wet end of the papermaking machine.
For example, in accordance with certain embodiments disclosed herein, a strength aid is added to a cellulosic fiber suspension in the papermaking process. The strength aid may include, for example, a natural strength aid and/or a synthetic strength aid. Illustrative, non-limiting examples of strength aids include a cationic glyoxalated polyacrylamide (GPAM) polymer, an anionic GPAM polymer, an amphoteric polymer with an overall negative charge, an amphoteric polymer with an overall positive charge, a cationic polyacrylamide polymer, an anionic polyacrylamide polymer, starch, and any combination thereof. In some embodiments, the strength aid excludes starch.
In certain embodiments, the strength aid comprises an associative polymer. The associative polymer comprises an associative monomer unit, an additional monomer unit, a monomer unit derived from a monomer of Formula I, and optionally a piperidine-2,6-dione unit, wherein the piperidine-2,6-dione is formed upon cyclization of an acrylamide nitrogen of the monomer unit derived from a monomer of Formula I on a carbonyl of the additional monomer unit. In some embodiments, the associative polymer has a weight average molecular weight of about 10 kDa to about 2,000 kDa.
Illustrative, non-limiting examples of additional monomer units include a monomer of Formula I, 2-(dimethylamino)ethyl acrylate (“DMAEA”), 2-(dimethylamino)ethyl methacrylate (“DMAEM”), 3-(dimethylamino)propyl methacrylamide (“DMAPMA”), 3-(dimethylamino)propyl acrylamide (“DMAPA”), 3-methacrylamidopropyl-trimethyl-ammonium chloride (“MAPTAC”), 3-acrylamidopropyl-trimethyl-ammonium chloride (“APTAC”), N-vinyl pyrrolidone (“NVP”), N-vinyl acetamide, hydroxyethyl methacrylate, hydroxyethyl acrylate, diallyldimethylammonium chloride (“DADMAC”), diallylamine, vinylformamide, 2-(acryloyloxy)—N,N,N-trimethylethanaminium chloride (“DMAEA.MCQ”), 2-(methacryloyloxy)—N,N,N-trimethylethanaminium chloride (“DMAEM.MCQ”), N,N-dimethylaminoethyl acrylate benzyl chloride (“DMAEA.BCQ”), N,N-dimethylaminoethyl methacrylate benzyl chloride (“DMAEM.BCQ”), 2-acrylamido-2-methylpropane sulfonic acid (“AMPS”), 2-acrylamido-2-methylbutane sulfonic acid (“AMBS”), [2-methyl-2-[(1-oxo-2-propenyl)amino]propyl]-phosphonic acid, methacrylic acid, acrylic acid, salts thereof, and combinations thereof.
In some embodiments, the associative polymer comprises a monomer unit derived from a monomer of Formula I:
wherein R1 is H or C1-C4 alkyl (e.g., methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, or tert-butyl) and each R2 is independently H or an organic group. As used herein, the term “organic group” refers to an alkyl group, an aryl group, a fluoroalkyl group, or a fluoroaryl group. In certain embodiments, the monomer unit derived from a monomer of Formula I is considered an additional monomer unit.
In certain embodiments of the substituent R2, the organic group is a C1-C6 alkyl group (i.e., 1, 2, 3, 4, 5, or 6 carbon units in length). In some embodiments, the C1-C6 alkyl group is saturated, unsaturated, branched, straight-chained, cyclic, or a combination thereof.
The associative monomer unit may be, for example, a nonionic associative monomer unit. Generally, the nonionic associative monomer unit may be derived from an acrylate and/or an acrylamide monomer of Formula II:
wherein R3 is H or C1-C10 alkyl (e.g., (CH2)kCH3), wherein k is an integer from 0 to 9 (i.e., 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9), X is O or NH, m, n, and o are independently integers from 0 to 100, wherein when (n+o)≤3, m is at least 7, each Y1 and Y2 are independently H or C1-C4 alkyl (e.g., methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, or tert-butyl), and R4 is H or a hydrophobic group.
The associative polymer may comprise, for example, an associative polymer of Formula AP1:
wherein E is one or more associative monomer unit(s), F is one or more additional monomer unit(s), G is one or more monomer unit(s) derived from a monomer of Formula I, H is optionally present and is one or more piperidine-2,6-dione unit(s), wherein the one or more piperidine-2,6-dione(s) are formed upon cyclization of an acrylamide nitrogen of the monomer unit derived from the monomer of Formula I (“G”) on a carbonyl of the additional monomer unit (“F”). The associative polymer may have a weight average molecular weight of about 10 kDa to about 2,000 kDa.
As an illustrative, non-limiting example, the associative polymer may comprise formula AP3:
wherein E is one or more associative monomer unit(s), E″ is a mole percentage value of from about 0.005 to about 10, F is one or more additional monomer unit(s), F″ is a mole percentage value of from about 0.005 to about 90, G is one or more monomer unit(s) derived from a monomer of Formula I, G″ is a mole percentage value of from about 10 to about 99.99, H is one or more piperidine-2,6-dione unit(s), wherein the one or more piperidine-2,6-dione(s) are formed upon cyclization of an acrylamide nitrogen of the monomer unit derived from a monomer of Formula I (“G”) on a carbonyl of the additional monomer unit (“F”), and H″ is a mole percentage value of from about 0 to about 10.
In some embodiments, the associative polymer comprises formula AP3:
wherein E is one or more associative monomer unit(s), E″ is a mole percentage value of from about 0.005 to about 10, F is one or more additional monomer unit(s), F″ is a mole percentage value of from about 0.005 to about 90, G is one or more monomer unit(s) derived from a monomer of Formula I, G″ is a mole percentage value of from about 10 to about 99.99, H is one or more units of the formula
wherein R1 is H or C1-C4 alkyl (e.g., methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, or tert-butyl) and R2 is H or an organic group, and H″ is a mole percentage value of from about 0 to about 10. In certain embodiments, R1 and R2 are hydrogen.
The foregoing strength aids are further described in U.S. Pat. No. 10,920,065, the contents of which are expressly incorporated by reference into the present application in their entirety.
In some embodiments, the strength aid comprises a treatment polymer chemically and/or physically entangled and/or embedded in a colloidal aluminum hydroxide and/or colloidal ferric hydroxide complex. The complex may be in the form of a colloidal particle. The treatment polymer may include one or more anionic monomers, one or more cationic monomers, one or more non-ionic monomers, one or more zwitterionic monomers, or any combination of these monomers. In some embodiments, the treatment polymer has a net negative charge and in other embodiments, the treatment polymer has a net positive charge or a neutral charge. In certain embodiments, the treatment polymer is water-soluble. In some embodiments, the treatment polymer comprises a carboxylic acid group. The strength aid of the present paragraph is further described in U.S. Patent Application Publication No. 2023/078847, the contents of which are expressly incorporated by reference into the present application in their entirety.
In accordance with certain embodiments disclosed herein, a dewatering agent is added to the cellulosic fiber suspension in the papermaking process. The dewatering agent may comprise a polymer, such as a polymer having a reduced specific viscosity (RSV) from about 2.5 to about 5.5 dL/g, about 3.5 to about 4.5 dL/g, about 3.5 to about 5.5 dL/g, about 2.5 to about 4.5 dL/g, about 3 dL/g, about 4 dL/g, or about 5 dL/g.
The RSV is measured at a given polymer concentration and temperature and calculated as follows:
wherein η is viscosity of the polymer, η0 is viscosity of the solvent at the same temperature, an t is elution time of polymer, to is elution time of solvent, and c is concentration (g/dL) of the polymer in solution. In accordance with the present disclosure, the RSV measurements were carried out with about 2,400 ppm (0.24 wt. %) of active polymer in the solvent, which was 1 M NaNO3.
The present inventors carried out extensive experimentation to unexpectedly discover a RSV range where the presently disclosed technology performs exceptionally well. For example, it was discovered that if the RSV is greater than about 5.5, significant flocculation occurs and sheet formation is impaired. If the RSV is below about 2.5, the polymer may not synergistically enhance the performance of the strength aid.
The polymer of the dewatering agent may comprise, for example, a solution polymer, a latex polymer, a dry form polymer, or any combination thereof. The polymer may comprise, for example, an anionic monomer, a non-ionic monomer, a cationic monomer, a zwitterionic monomer, or any combination thereof.
In certain aspects, the polymer comprises a cationic monomer. The polymer may comprise, for example, from about 20 mol % to about 100 mol % of the cationic monomer. As additional, non-limiting examples, the polymer may comprise from about 20 mol % to about 90 mol %, about 20 mol % to about 80 mol %, about 20 mol % to about 70 mol %, about 20 mol % to about 60 mol %, about 20 mol % to about 50 mol %, about 20 mol % to about 40 mol %, about 20 mol % to about 30 mol %, about 30 mol % to about 100 mol %, about 40 mol % to about 100 mol %, about 50 mol % to about 100 mol %, about 60 mol % to about 100 mol %, about 70 mol % to about 100 mol %, about 80 mol % to about 100 mol %, about 90 mol % to about 100 mol %, about 35 mol %, about 45 mol %, about 55 mol %, about 65 mol %, about 75 mol %, about 85 mol %, or about 95 mol % of the cationic monomer.
The cationic monomer is not particularly limited and may be selected from, for example, a dialkylaminoalkyl acrylate or a salt thereof, a dialkylaminoalkyl methacrylate or a salt thereof, dimethylaminoethyl acrylate methyl chloride quaternary salt, dimethylaminoethyl acrylate methyl sulfate quaternary salt, dimethylaminoethyl acrylate benzyl chloride quaternary salt, dimethylaminoethyl acrylate sulfuric acid salt, dimethylaminoethyl acrylate hydrochloric acid salt, dimethylaminoethyl methacrylate methyl chloride quaternary salt, dimethylaminoethyl methacrylate methyl sulfate quaternary salt, dimethylaminoethyl methacrylate benzyl chloride quaternary salt, dimethylaminoethyl methacrylate sulfuric acid salt, dimethylaminoethyl methacrylate hydrochloric acid salt, a dialkylaminoalkyl acrylamide or a salt thereof, a dialkylaminoalkyl methacrylamide or a salt thereof, acrylamidopropyltrimethylammonium chloride, dimethylaminoethyl acrylate methyl chloride quaternary salt, dimethylaminoethyl acrylate benzyl chloride quaternary salt, dimethylaminoethyl methacrylate methyl chloride quaternary salt, dimethylaminoethyl methacrylate benzyl chloride quaternary salt, methacrylarnidopropyl trimethylammonium chloride, dimethylaminopropyl acrylamide methyl sulfate quaternary salt, dimethylaminopropyl acrylamide sulfuric acid salt, dimethylaminopropyl acrylamide hydrochloric acid salt, methacrylamidopropyltrimethylammonium chloride, dimethylaminopropyl methacrylamide methyl sulfate quaternary salt, dimethylaminopropyl methacrylamide sulfuric acid salt, dimethylaminopropyl methacrylamide hydrochloric acid salt, diethylaminoethylacrylate, diethylaminoethylmethacrylate, diallyldiethylammonium chloride, diallyldimethylammonium chloride, and any combination thereof.
When the polymer comprises a non-ionic monomer, it may be selected from, for example, acrylamide, methacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, N-isopropylacrylamide, N-vinylformamide, N-vinylmethylacetamide, N-vinyl pyrrolidone, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, N-tert-butylacrylamide, N-methylolacrylamide, diallylamine, allylamine, and any combination thereof.
When the polymer comprises an anionic monomer, it may be selected from, for example, acrylic acid, sodium acrylate, ammonium acrylate, methacrylic acid, sodium methacrylate, ammonium methacrylate, 2-acrylamido-2-methylpropane sulfonic acid (AMPS), a sodium salt of AMPS, sodium vinyl sulfonate, styrene sulfonate, maleic acid, a sodium salt of maleic acid, an ammonium salt of maleic acid, sulfonate itaconate, sulfopropyl acrylate, sulfopropyl methacrylate, a sulphonic acid, sulfomethylated acrylamide, allyl sulfonate, sodium vinyl sulfonate, itaconic acid, acrylamidomethylbutanoic acid, fumaric acid, vinylphosphonic acid, vinylsulfonic acid, allylphosphonic acid, sulfomethylated acrylamide, phosphonomethylated acrylamide, and any combination thereof.
When the polymer comprises a zwitterionic monomer, it may be selected from, for example, N,N-dimethyl-N-acryloyloxyethyl-N-(3-sulfopropyl)-ammonium betaine, N,N-dimethyl-N-acrylamidopropyl-N-(2-carboxymethyl)-ammonium betaine, N,N-dimethyl-N-acrylamidopropyl-N-(3-sulfopropyl)-ammonium betaine, N,N-dimethyl-N-acrylamidopropyl-N-(2-carboxymethyl)-ammonium betaine, 2-(methylthio)ethyl methacryloyl-S-(sulfopropyl)-sulfonium betaine, 2-[(2-acryloylethyl)dimethylammonio]ethyl 2-methyl phosphate, 2-(acryloyloxyethyl)-2′-(trimethylammonium)ethyl phosphate, [(2-acryloylethyl)dimethylammonio]methyl phosphonic acid, 2-methacryloyloxyethyl phosphorylcholine, 2-[(3-acrylamidopropyl)dimethylammonio]ethyl 2′-isopropyl phosphate, 1-vinyl-3-(3-sulfopropyl)imidazolium hydroxide, (2-acryloxyethyl) carboxymethyl methylsulfonium chloride, 1-(3-sulfopropyl)-2-vinylpyridinium betaine, N-(4-sulfobutyl)—N-methyl-N, N-diallylamine ammonium betaine, N,N-diallyl-N-methyl-N-(2-sulfoethyl)ammonium betaine, and any combination thereof.
In certain illustrative, non-limiting embodiments, the dewatering agent includes a polymer comprising 2-dimethylaminoethyl acrylate (DMAEA) methyl chloride quaternary (MCQ) salt and acrylamide, 2-dimethylaminoethyl methacrylate (DMAEM) MCQ salt and acrylamide, diallyldimethylammonium chloride (DADMAC) and acrylamide, DMAEA and acrylamide, DMAEM and acrylamide, and any combination thereof. In certain illustrative, non-limiting embodiments, the dewatering agent includes a polymer comprising a member selected from the group consisting of DMAEA, DMAEM, DADMAC, a salt of any of the foregoing, and any combination thereof.
As additional examples, the dewatering agent of the present disclosure may comprise a polymer including DMAEA.MCQ and acrylamide and optionally one or more of water, a paraffin solvent, sorbitan monooleate, ethoxylated sorbitan monostearate, and/or a C10-C16 ethoxylated alcohol.
The weight average molecular weight of the dewatering agent polymer is not particularly limited and may be selected from, for example, about 1,000,000 Da to about 10,000,000 Da, about 1,000,000 Da to about 9,000,000 Da, about 1,000,000 Da to about 8,000,000 Da, about 1,000,000 Da to about 7,000,000 Da, about 1,000,000 Da to about 6,000,000 Da, about 1,000,000 Da to about 5,000,000 Da, about 1,000,000 Da to about 4,000,000 Da, about 1,000,000 Da to about 3,000,000 Da, about 1,000,000 Da to about 2,000,000 Da, about 2,000,000 Da to about 10,000,000 Da, about 3,000,000 Da to about 10,000,000 Da, about 4,000,000 Da to about 10,000,000 Da, about 5,000,000 Da to about 10,000,000 Da, about 6,000,000 Da to about 10,000,000 Da, about 7,000,000 Da to about 10,000,000 Da, about 8,000,000 Da to about 10,000,000 Da, about 9,000,000 Da to about 10,000,000 Da, about 2,000,000 Da to about 7,000,000 Da, about 2,000,000 Da to about 6,000,000 Da, about 2,000,000 Da to about 5,000,000 Da, about 2,000,000 Da to about 4,000,000 Da, about 3,000,000 Da to about 4,000,000 Da, about 3,000,000 Da to about 5,000,000 Da, about 3,000,000 Da to about 6,000,000 Da, about 3,000,000 Da, about 3,500,000 Da, about 3,700,000 Da, about 3,900,000 Da, about 4,000,000 Da, or about 4,500,000 Da.
The strength aid and the dewatering agent may be added to various sections of a papermaking machine, such as the wet end. Additionally, the components may be added in any order continuously or intermittently. For example, the strength aid may be added before the dewatering agent. Alternatively or additionally, the strength aid may be added after the dewatering agent. In some embodiments, the strength aid is added before, after, and/or with the dewatering agent.
Adding a cationic dewatering agent first may help clean up/engage/neutralize any anionic trash in the furnish so that there are less contaminants to interfere with the strength agent when it is subsequently added and thus, better performance of the strength agent may be realized. For example, when a dewatering agent is used with a strength aid, such as anionic GPAM, the dewatering agent may form anchor sites on the fiber and help absorb the strength aid onto the fiber surface. If an anionic strength agent is used in connection with a cationic dewatering agent, for example, the anionic strength agent may bind to the fiber as well as to the cationic dewatering agent.
The strength aid and the dewatering agent may be added, for example, to the wet end of the papermaking machine. In some embodiments, the strength aid and the dewatering agent are added to a cellulosic fiber suspension. In certain embodiments, the strength aid and the dewatering agent may be co-fed into the cellulosic fiber suspension.
The terms “co-feed,” “co-feeding,” “co-fed,” and the like refer to the addition of two or more components, ingredients, chemicals, such as a dewatering agent and a strength aid, to a location, such as a reaction vessel, a storage container, the wet end of a papermaking machine, a cellulosic fiber suspension, and/or a different section of the papermaking machine, separately but essentially/substantially at the same time and location. For example, two components, such as a dewatering agent and a strength aid, may be fed into a location in the wet end of a papermaking machine, such as a cellulosic fiber suspension, through separate injection pipes. Each pipe may continuously or intermittently inject chemical at the same time to a single location in the papermaking machine or to two or more locations in the papermaking machine that are in close proximity to each other (e.g., within about 1 to about 12 inches, such as from about 1 to about 10 inches, from about 1 to about 8 inches, or from about 1 to about 6 inches).
For example, an injection pipe may lead to a location in the papermaking furnish and the pipe may inject dewatering agent into the fiber suspension. An adjacent pipe may be present and it may add additional chemical, such as strength aid. Each chemical addition may be continuous or intermittent, for example. Since the injection pipes are adjacent or substantially adjacent to one another, the chemicals are fed to substantially the same location in the fiber suspension at substantially the same time.
In accordance with certain aspects of the present disclosure, the strength aid and the dewatering agent are added to a medium, such as a fiber suspension, in a papermaking process, prior to a forming section. Illustrative, non-limiting examples of locations where the chemicals may be added include to a headbox, before the headbox, to a mixing chest, before a fan pump, between the fan pump and a pressure screen, after the pressure screen, to a thin stock, to a thick stock, or any combination thereof. The dewatering agent may be added to one or more of the foregoing locations and the strength aid may be added to one or more of the foregoing locations. The dewatering agent and the strength aid may be added to the same location and/or to a different location.
The amount of the dewatering agent to be added is not particularly limited and may be chosen based on various factors. For example, the dewatering agent may be added in an amount ranging from about 0.1 kg/T to about 5 kg/T as dry solid, based on a dry weight of the cellulosic fiber suspension, such as from about 0.1 kg/T to about 5 kg/T, about 0.1 kg/T to about 4 kg/T, about 0.1 kg/T to about 3 kg/T, about 0.1 kg/T to about 2 kg/T, about 0.1 kg/T to about 1 kg/T, about 0.1 kg/T to about 0.5 kg/T, about 0.3 kg/T to about 5 kg/T, about 0.3 kg/T to about 4 kg/T, about 0.3 kg/T to about 3 kg/T, about 0.3 kg/T to about 2 kg/T, about 0.7 kg/T to about 5 kg/T, about 0.7 kg/T to about 3 kg/T, about 1 kg/T to about 5 kg/T, or about 1 kg/T to about 3 kg/T.
The amount of strength aid to be added is not particularly limited and may be chosen based on various factors. For example, the strength aid may be added in an amount ranging from about 0.025% to about 1.0% dry solids, based on a dry weight of the cellulosic fiber suspension, such as about 0.05% to about 1.0%, about 0.08% to about 1.0%, about 0.1% to about 1.0%, about 0.3% to about 1.0%, about 0.5% to about 1.0%, about 0.75% to about 1.0%, about 0.1% to about 0.75%, or about 0.1% to about 0.5%.
Various additional chemicals can optionally be added to the papermaking process along with, before, and/or after the strength aid and/or dewatering agent. For example, methods disclosed herein may include adding to the cellulosic fiber suspension an additive selected from the group consisting of a solvent, sorbitan monooleate, ethoxylated sorbitan monostearate, an inorganic siliceous microparticle, an alcohol, an acid, a coagulant, a flocculant, a colorant, a filler, a retention aid, a drainage aid, a biocide, a defoamer, a surfactant, an enzyme, a brightening agent, a sizing agent, a dispersant, a bulk agent, a pigment, and any combination thereof.
For example, in certain embodiments, a solvent, such as a paraffinic solvent, may be added and/or an alcohol may be added, such as an ethoxylated alcohol. The ethoxylated alcohol may be a C10-C16 ethoxylated alcohol, for example, such as a C10-C14 ethoxylated alcohol, a C10-C12 ethoxylated alcohol, a C12-C16 ethoxylated alcohol, or a C14-C16 ethoxylated alcohol.
The medium in which the chemicals are added is not particularly limited and may be any medium in the papermaking process. For example, the compounds and/or compositions may be added to a cellulosic fiber suspension. The compounds and/or compositions can enhance drainage in various mediums, such as high conductivity, high charge papermaking suspensions, with no detrimental effect in retention or formation.
In some embodiments, the cellulosic fiber suspension may comprise a high charge. Particle charge demand may be measured by, for example, a BTG particle charge detector. In some embodiments, the medium where the chemicals are added, such as a fiber suspension, comprises a charge of about −200 meq/L or less, such as about −200 meq/L to about −5,000 meq/L, about −200 meq/L to about −3,000 meq/L, about −200 meq/L to about −1,000 meq/L, or about −200 meq/L to about −500 meq/L.
In some embodiments, the cellulosic fiber suspension may comprise a conductivity of at least about 1 mS/cm. For example, the fiber suspension may comprise a conductivity of about 1 mS/cm to about 20 mS/cm, such as from about 1 mS/cm to about 18 mS/cm, about 1 mS/cm to about 16 mS/cm, about 1 mS/cm to about 14 mS/cm, about 1 mS/cm to about 12 mS/cm, about 1 mS/cm to about 10 mS/cm, about 1 mS/cm to about 8 mS/cm, about 1 mS/cm to about 6 mS/cm, about 1 mS/cm to about 4 mS/cm, about 2 mS/cm to about 20 mS/cm, about 4 mS/cm to about 20 mS/cm, about 6 mS/cm to about 20 mS/cm, about 8 mS/cm to about 20 mS/cm, about 10 mS/cm to about 20 mS/cm, about 12 mS/cm to about 20 mS/cm, about 14 mS/cm to about 20 mS/cm, about 16 mS/cm to about 20 mS/cm, or about 18 mS/cm to about 20 mS/cm.
The methods, compounds, and compositions disclosed herein improve strength aid performance and increase strength of paper products produced according to the methods disclosed herein. The paper products are not limited and may include, for example, any end product of a papermaking process, such as writing paper, printer paper, tissue paper, cardboard, paperboard, and packaging paper.
The foregoing may be better understood by reference to the following examples, which are intended for illustrative purposes and are not intended to limit the scope of the disclosure or its application in any way.
Various dewatering agents and strength aids were dosed into a pulp slurry and paper sheets were produced therefrom. In the first test, a dewatering agent comprising a cationic latex copolymer of DMAEA.MCQ and acrylamide (RSV of about 4 dL/g) was dosed into the slurry at about 2 lb/ton and no strength aid was added. In the second test, about 8 lb/ton of anionic GPAM was added and no dewatering agent was added. In the third test, about 8 lb/ton of anionic GPAM was added and about 2 lb/ton of the cationic latex copolymer of DMAEA.MCQ and acrylamide was added. In the fourth test, about 8 lb/ton of cationic GPAM was added and no dewatering agent was added. In the fifth test, about 8 lb/ton of cationic GPAM was added and about 2 lb/ton of the cationic latex copolymer of DMAEA.MCQ and acrylamide was added. In a sixth test, about 8 lb/ton of a cationic polyampholyte comprising acrylamide, DMAEA.MCQ, and acrylic acid was added and no dewatering agent was added. In a seventh test, about 8 lb/ton of the cationic polyampholyte comprising acrylamide, DMAEA.MCQ, and acrylic acid was added and about 2 lb/ton of the cationic latex copolymer of DMAEA.MCQ and acrylamide was added. In an eight test, about 2 lb/ton of the cationic latex copolymer of DMAEA.MCQ and acrylamide was added and about 8 lb/ton of the cationic polyampholyte comprising acrylamide, DMAEA.MCQ, and acrylic acid was added. In a ninth test, no dewatering agent was added and about 20 lb/ton of cationic starch was added. In a tenth test, about 2 lb/ton of the cationic latex copolymer of DMAEA.MCQ and acrylamide was added and about 20 lb/ton of cationic starch was added. The strength of the resulting paper sheets was tested. Results are shown in
Specifically,
Although most of the combinations performed unexpectedly well, the top performer was a combination of cationic GPAM and a cationic latex copolymer of DMAEA.MCQ and acrylamide.
All of the compositions and methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While this invention may be embodied in many different forms, there are described in detail herein specific preferred embodiments of the invention. The present disclosure is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. In addition, unless expressly stated to the contrary, use of the term “a” is intended to include “at least one” or “one or more.” For example, “a strength aid” is intended to include “at least one strength aid” or “one or more strength aids.”
Any ranges given either in absolute terms or in approximate terms are intended to encompass both, and any definitions used herein are intended to be clarifying and not limiting. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges (including all fractional and whole values) subsumed therein.
Any composition disclosed herein may comprise, consist of, or consist essentially of any element, component and/or ingredient disclosed herein or any combination of two or more of the elements, components or ingredients disclosed herein.
Any method disclosed herein may comprise, consist of, or consist essentially of any method step disclosed herein or any combination of two or more of the method steps disclosed herein.
The transitional phrase “comprising,” which is synonymous with “including,” “containing,” or “characterized by,” is inclusive or open-ended and does not exclude additional, un-recited elements, components, ingredients and/or method steps.
The transitional phrase “consisting of” excludes any element, component, ingredient, and/or method step not specified in the claim.
The transitional phrase “consisting essentially of” limits the scope of a claim to the specified elements, components, ingredients and/or steps, as well as those that do not materially affect the basic and novel characteristic(s) of the claimed invention.
Unless specified otherwise, all molecular weights referred to herein are weight average molecular weights and all viscosities were measured at 25° C. with neat (not diluted) polymers.
As used herein, the term “about” refers to the cited value being within the errors arising from the standard deviation found in their respective testing measurements, and if those errors cannot be determined, then “about” may refer to, for example, within 5%, 4%, 3%, 2%, or 1% of the cited value.
Furthermore, the invention encompasses any and all possible combinations of some or all of the various embodiments described herein. It should also be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.
| Number | Date | Country | |
|---|---|---|---|
| 63508382 | Jun 2023 | US |
