Improved retention of engineered cellulose additives using synergistic cationic polymer combinations

Abstract

The present invention relates generally to a novel combination comprising two different cationic polymers and an engineered cellulose additive (ECA), and its use to promote retention of the engineered cellulose additive (ECA) into anionic fibers and colloids and fibrous webs during papermaking, optionally wherein the papermaking process uses predominantly or exclusively kraft fiber or native fiber.

Description

[0001] Related Applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 387,298, filed on December 14, 2022, and Finnish Application No. 20235307, filed on March 16, 2023, the contents of both of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure generally relates to novel combinations of cationic polymers and engineered cellulose additives (ECA) and the use of such novel combinations in papermaking, preferably in papermaking processes using a fiber furnish consisting mainly or solely of kraft or virgin fibers. Background Art

[0004] In papermaking, strength is an important property of the finished product and can be achieved by varying the amount or type of fibers used or by using chemical additives to provide more binding sites or higher binding energy. Additives used during papermaking to enhance the strength of the final paper product include carboxymethyl cellulose (CMC) and engineered cellulose additives (ECA).

[0005] In particular, engineered cellulose additives (ECA) have been used in papermaking to replace virgin fibers, as a starch substitute, and as a strength enhancer. Using ECA increases the strength of the paper web by providing more hydrogen bonding sites without using expensive fiber sources. ECA products are anionic and do not adhere to anionic fiber sources by themselves.

[0006] CMC is more commonly used to increase the strength of the paper web. ECA differs from CMC in terms of its solubility, charge density, and molecular weight (Mw). CMC is completely soluble in water and has an Mw range of 10 kDa to 1 MDa. ECA exists to some extent as a hybrid technology in the space between CMC and nanocellulose / microfibrillated cellulose (MFC). ECA has a lower charge than CMC and has a portion that exists as a dissolved material and other portions with lengths in the range of 200 nm to 300 nm. The ability to retain the dissolved colloidal fraction as well as the nanoscale fraction is important for the strength performance of ECA.

[0007] Both ECA and CMC additives rely on cationic additives, and in particular cationic polymers, in order to be chemically retained in the fiber web. However, even though ECA is anionic in charge, and even though cationic polymer additives currently used to promote the retention of ECA in the fiber web are added, it is difficult for ECA to be retained in the papermaking furnish. In particular, a large amount of ECA is "lost" during the current papermaking process because they are not effectively fixed to the anionic fibers or retained in the fiber web. Thus, these ECAs are not included in the final produced paper products. This is disadvantageous because it requires the addition of more ECA and / or cationic polymers, which increases the cost of the papermaking process and furthermore may result in paper products with insufficient strength properties.

[0008] Based on the foregoing, there is a need for improved methods and polymer additives for manufacturing paper and / or paperboard that promote the retention of strength additives such as ECA on anionic fibers and in the fiber web. The present invention achieves these objects as described herein. Summary of the Invention

[0009] A specific object of the present invention is to provide a papermaking method for promoting the retention of ECA to anionic fibers and the fiber web during papermaking, the method comprising using a high charge low molecular weight fast inverse polymer (fixing polymer), an anionic ECA product, and a relatively low charge high molecular weight fast inverse polymer (retention polymer).

[0010] A specific object of the present invention is to provide a papermaking method that includes adding an engineered cellulose additive (ECA), optionally to replace virgin fibers and / or starch and / or as a strength enhancer, the method comprising adding the following:

[0011] (i) A high charge fast inverse fixing copolymer that includes Q9 (cationic) and acrylamide monomers ("fixing polymer"),

[0012] (ii) ECA, and

[0013] (iii) A high molecular weight fast inverse cationic retention polymer that includes Q9 (cationic) and acrylamide monomers ("retention polymer");

[0014] wherein each of them is added separately to the papermaking system in the above order.

[0015] A specific object of the present invention is to provide a method for treating fiber raw materials and / or process water used in pulp, paper, or paperboard production, the method comprising obtaining the fiber raw materials and / or process water, and treating the fiber raw materials and / or process water with the following:

[0016] (i) A high-charge rapid inverse fixing copolymer, which comprises Q9 (cation) and acrylamide monomers (“fixing polymer”),

[0017] (ii) Anionic ECA, and

[0018] (iii) A high-molecular-weight rapid inverse cationic retention polymer, which comprises Q9 (cation) and acrylamide monomers (“retention polymer”);

[0019] Wherein each is added separately to the furnish and / or process water.

[0020] A specific object of the present invention is to provide a method for manufacturing paper or cardboard, wherein the fibrous web is formed from an aqueous suspension of fibers, and the method comprises:

[0021] - Providing an aqueous fiber suspension, which mainly or only contains virgin fibers or kraft fibers, and optionally further contains some recycled fiber materials and / or coated broke,

[0022] - Optionally diluting the aqueous fiber suspension,

[0023] - Delivering the aqueous fiber suspension to a headbox, draining the aqueous fiber suspension on a wire screen to form a wet fibrous web, and

[0024] - Pressing and drying the wet fibrous web to obtain a web of paper or cardboard, and the method comprises separately adding (i) a high-charge rapid inverse fixing copolymer containing Q9 (cation) and acrylamide monomers, (ii) ECA, and (iii) a high-molecular-weight rapid inverse cationic retention polymer containing Q9 (cation) and acrylamide monomers, wherein each of (i), (ii) and (iii) is added separately during manufacturing.

[0025] A specific object of the present invention is to provide a method as described above, wherein the high-charge rapid inverse fixing copolymer (fixing polymer) promotes the fixing of ECA and optionally other colloidal particles to anionic fibers, and / or the high-molecular-weight rapid inverse cationic polymer (retention polymer) promotes the retention of ECA and optionally fines and other colloidal particles in the fibrous web.

[0026] A specific object of the present invention is to provide a method as described above, wherein the high-charge rapid inverse fixing copolymer (fixing polymer) promotes the fixing of ECA and optionally other colloidal particles to anionic fibers, and / or the high-molecular-weight rapid inverse cationic polymer (retention polymer) promotes the retention of ECA and optionally fines and other colloidal particles in the fibrous web.

[0027] A specific object of the present invention is to provide a method as described above, wherein the high-charge fast-inverting fixing polymer comprises 30 mol% to 40 mol% of Q9 monomer and has a standard viscosity (SV) between 1.7 cps and 2.0 cps.

[0028] A specific object of the present invention is to provide a method as described above, wherein the high-molecular-weight fast-inverting cationic retention copolymer comprises 20 mol% to 30 mol% of Q9 monomer and has a standard viscosity (SV) between 3.0 cPs and 3.5 cPs.

[0029] A specific object of the present invention is to provide a method as described above, wherein

[0030] (i) First, add the high-charge fast-inverting fixing polymer to the papermaking system;

[0031] (ii) After adding the high-charge fast-inverting fixing polymer, add ECA to the papermaking system; and

[0032] (iii) After adding ECA to the papermaking system, add the high-molecular-weight fast-inverting cationic retention polymer.

[0033] A specific object of the present invention is to provide a method as described above, wherein the combined dosage of the retention polymer and the fixing polymer is equal to or greater than ECA.

[0034] A specific object of the present invention is to provide a method as described above, wherein the dosage range of the fixing polymer is 0.1 kg to 5 kg per ton.

[0035] A specific object of the present invention is to provide a method as described above, wherein the dosage range of the retention polymer is 0.1 kg to 5 kg per ton.

[0036] A specific object of the present invention is to provide a method as described above, wherein the combined dosage range of the fixing polymer and the retention polymer is 0.2 kg to 5 kg per ton.

[0037] A specific object of the present invention is to provide a method as described above, wherein the dosage range of ECA is 0.25 kg to 5 kg per ton.

[0038] A specific object of the present invention is to provide a method as described above, wherein the intervals between steps (i) and (ii) and (iii) are sufficient to achieve sufficient mixing, and according to the shear dynamics during mixing, this interval is usually at least 3 seconds to 5 minutes.

[0039] A specific object of the present invention is to provide a method as described above, which comprises one or more other additives commonly used in papermaking, such as dyes, starches, microbicides, other fixing agents or retention aids, sizing agents, etc.

[0040] A specific object of the present invention is to provide a method as described above, wherein

[0041] (i) The high-charge rapid inverse fixing polymer enhances the fixing of ECA to anionic fibers without disrupting the formation of the paper, optionally at a high polymer dosage level;

[0042] (ii) The high-charge rapid inverse fixing polymer promotes the fixing of anionic ECA products and other anionic colloidal particles to anionic fibers;

[0043] (iii) The high-charge rapid inverse fixing polymer promotes the fixing of ECA more effectively than traditional charge fixing / control agents (CCA) such as polyacrylamide-DADMAC dispersions, polyamines, and poly-DADMAC solution polymers;

[0044] (iv) The high molecular weight rapid inverse cationic retention polymer interacts more effectively with colloids and fines than linear and conventional high Mw cationic polymers (typical SV range = 4.5 cPs to 5.5 cPs);

[0045] (v) The high molecular weight rapid inverse cationic retention polymer enhances the total retention of ECA, fines, and fibers on the paper machine;

[0046] (vi) The combination of the high molecular weight rapid inverse cationic fixing polymer and the high molecular weight rapid inverse cationic retention polymer causes a synergistic effect on the drainage of the paper machine;

[0047] (vii) The combination of the high molecular weight rapid inverse cationic fixing polymer and the high molecular weight rapid inverse cationic retention polymer causes a synergistic effect on the total first-pass retention of engineered cellulose additives (ECA) on ECA-enhanced paper grades;

[0048] (viii) The combination of the high molecular weight rapid inverse cationic fixing polymer and the high molecular weight rapid inverse cationic retention polymer promotes dye retention;

[0049] (ix) The combination of the high molecular weight rapid inverse cationic fixing polymer and the high molecular weight rapid inverse cationic retention polymer reduces the amount of dye required;

[0050] (x) The combination of the high molecular weight rapid inverse cationic fixing polymer and the high molecular weight rapid inverse cationic retention polymer reduces the amount of filler required;

[0051] (xi) The combination of high molecular weight fast reverse phase cationic fixing polymers and high molecular weight fast reverse phase cationic retention polymers improves dryer efficiency;

[0052] (xii) The combination of high molecular weight fast reverse phase cationic fixing polymers and high molecular weight fast reverse phase cationic retention polymers promotes the retention of dyes and / or fillers;

[0053] (xiii) The combination of high molecular weight fast reverse phase cationic fixing polymers and high molecular weight fast reverse phase cationic retention polymers reduces the amount of starch required;

[0054] (xiv) The combination of high molecular weight fast reverse phase cationic fixing polymers and high molecular weight fast reverse phase cationic retention polymers has a synergistic effect on the retention of ECA, fines and fibers on the paper produced;

[0055] (xv) Any of the foregoing combinations.

[0056] A specific object of the present invention is to provide a method as described above, wherein the total dosage by weight of the high molecular weight fast reverse phase cationic fixing polymer and the high molecular weight fast reverse phase cationic retention polymer ranges from about 0.8 times to about 20 times the amount of ECA added to the papermaking system, about 1.0 times to about 10 times the amount of ECA, about 1.0 times to about 5.0 times the amount of ECA, about 1.0 times to about 3.0 times the amount of ECA, about 1.0 times to about 2.0 times the amount of ECA, or approximately equal to the amount of ECA.

[0057] A specific object of the present invention is to provide a method as described above, wherein the dosage ratio by weight of the high molecular weight fast reverse phase cationic fixing polymer and the high molecular weight fast reverse phase cationic retention polymer added to the papermaking system ranges from

[0058] (i) about 1 / 20 to about 20 / 1 by weight;

[0059] (ii) about 1 / 10 to about 10 / 1 by weight;

[0060] (iii) about 2 / 10 to about 10 / 2 by weight;

[0061] (iv) about 3 / 10 to about 10 / 3 by weight;

[0062] (vi) about 3 / 8 to about 8 / 3 by weight;

[0063] (vii) about 3 / 7 to about 7 / 3 by weight;

[0064] (viii) about 4 / 6 to about 6 / 4 by weight;

[0065] (ix) from about 5.5 / 4.5 to about 4.5 / 5.5 by weight; or

[0066] (x) about equal amounts by weight of a fast-inverting cationic retention polymer added to the papermaking system.

[0067] A specific object of the present invention is to provide a method as described above, wherein the polymer and ECA are added to a fiber furnish mainly comprising kraft fibers or virgin fibers. For example, the fiber furnish comprises at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, or even more preferably at least 80% or 90% by weight of kraft fibers or virgin fibers; and optionally comprises a substantially smaller amount of recycled fibers, such as 5% to 10% by weight of recycled fibers, and is optionally added to a dilute furnish or a thick furnish, preferably a thick furnish.

[0068] A specific object of the present invention is to provide a method as described above, which comprises using hard water, and / or (ii) some (e.g., up to 5% to 10% by weight) recycled fibers.

[0069] A specific object of the present invention is to provide a method as described above, wherein the polymer and ECA are added to a fluid, composition or machine used in the papermaking system.

[0070] A specific object of the present invention is to provide a method as described above, wherein

[0071] (i) Based on dry paper or board, the fiber suspension comprises at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, or even more preferably at least 80% or 100% by weight of kraft fibers or virgin fibers, and optionally may comprise some recycled fiber materials and / or coated broke;

[0072] (ii) The polymer and ECA are added separately to a fiber suspension having a viscosity higher than 30 g / l;

[0073] (iii) The polymer and ECA are added separately to a fiber suspension having a viscosity lower than 20 g / l;

[0074] (iv) Before washing and / or cleaning and / or thickening, the polymer and ECA are added to the fiber furnish, wherein the fiber furnish has a viscosity of less than about 4%, 2% or 1% (i.e., the dry mass percentage in the furnish);

[0075] (v) Before forming and / or pressing and / or drying, the polymer and ECA are added to the fiber furnish, wherein the fiber furnish optionally has a viscosity of about 15% to 35% (i.e., the dry mass percentage in the furnish);

[0076] (vi) adding the polymer and the ECA separately to a fiber suspension having a consistency higher than 20 g / l, optionally, wherein the ECA is added in an amount of about 0.1 kg to 5 kg per ton of paper or board produced;

[0077] (vii) the raw material contains starch;

[0078] (viii) the raw material contains up to 5 wt% to 10 wt% of a recycled fiber raw material containing a low level of fines;

[0079] (ix) the raw material contains up to 5 wt% to 10 wt% of a recycled fiber raw material containing a high level of fines;

[0080] (x) the raw material contains some recycled fibers, optionally up to 5 wt% to 10 wt%, which are obtained from a paper machine that uses only or mainly recycled paper;

[0081] (xi) the raw material contains some, optionally up to 5 wt% to 10 wt%, of fibers derived from recycled paper, old corrugated container board (OCC), mixed office waste (MOW), old magazines (OMG), unbleached kraft pulp, neutral sulfite semi-chemical (NCCS) pulp, and / or mechanical pulp;

[0082] (xii) the raw material contains at least 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt% or 100 wt% of kraft fibers or virgin fibers, and optionally, the pretreated fiber raw material may contain some fibers obtained from a papermaking process using a paper machine that uses at least 60 wt%, 70 wt%, 80 wt%, 90 wt% or 100 wt% of recycled fibers;

[0083] (xiii) the raw material contains some, optionally up to 5 wt% to 10 wt%, of OCC recycled fibers that contain about 5% of natural sizing press starch and starch gel that can optionally be recycled for the manufacture of paper or board;

[0084] (xiv) the raw material contains starch optionally derived from recycled fibers and / or mill broke fibers in the raw material and / or starch is added to the treated fiber raw material;

[0085] (xv) treating before or simultaneously with the addition of other cationic functional polymers or other papermaking chemicals; or

[0086] (xvi) any combination of the foregoing.

[0087] A specific object of the present invention is to provide a fibrous raw material for the production of pulp, paper or cardboard, which preferably comprises at least 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt% or 100 wt% of kraft fibers or virgin fibers, and which optionally comprises some fibers and / or broke fibers, and / or optionally comprises some starch, and which comprises a composition comprising a combination of a cationic polymer and an ECA according to any one of the preceding claims and / or has been treated with such a composition.

[0088] A specific object of the present invention is to provide paper or cardboard produced by the method according to any one of the preceding claims. Description of the Drawings

[0089] Figure 1 The effects of different fast-inverting polymers and conventional charge control agent (CCA) polymers on the drainage time in an existing DDA / retaining polymer system were compared, where ECA was added as a strength additive. The existing system uses a charge control agent (CCA) (such as a polyacrylamide-DADMAC emulsion) to fix the ECA to the fibers, and in addition also uses a conventional retaining polymer to retain fibers, fines and other papermaking additives. In these experiments, the effects of different dosages (kg / T) of a high-charge fast-inverting polymer fixative (Polymer A), a high-molecular-weight fast-inverting retaining polymer (Polymer B), a combination of Polymer A and Polymer B, and a conventional CCA polymer (a polyacrylamide-DADMAC dispersion) on the drainage rate were evaluated. The results showed that the combination of Polymer A (used to replace the CCA) and Polymer B (used to replace the conventional retention aid) improved the drainage time by 32% to 35%.

[0090] Figure 2 The effects of different fast-inverting polymers and conventional CCA polymers on the filtrate turbidity in an existing DDA / retaining polymer system were compared. The existing system again uses a charge control agent (CCA) to fix the ECA to the fibers, and in addition also uses a conventional retaining polymer to retain fibers, fines and other papermaking additives. In these experiments, the effects of different dosages (kg / T) of a high-charge fixative (Polymer A), a high-molecular-weight cationic retaining polymer (Polymer B), a combination of Polymer A and Polymer B, and a conventional CCA polymer (a polyacrylamide-DADMAC dispersion) on the filtrate turbidity were evaluated. The results showed that, compared with the existing DDA / retaining polymer system, the combination of Polymer A (used to replace the CCA) and Polymer B (used to replace the conventional retention aid) promoted the retention of ECA (as measured by turbidity).

[0091] Figure 3The effects of polymer A as a fixative for ECA and polymer B as a retention aid were compared in papermachine trials. In these experiments, a bleached, undyed grade NA papermachine was run using a combination of an amphoteric strength additive and starch to achieve strength targets. In these experiments, polymer A was added within 10 seconds of adding ECA. As shown by the results in the figure, the combination of ECA, polymer A (as a fixative), and polymer B (as a retention aid) provided the highest strength at the lowest dosage, as measured by ZDT (Z - dimensional tensile). As shown, the existing procedure requires 3.6 kg / T starch and 2.7 kg / T of an amphoteric polymer with added CCA to achieve the performance seen with the combination of polymer A and polymer B (3.6 kg / T starch, 0.9 kg / T ECA). As shown, no performance degradation was observed during the machine trials.

[0092] Figure 4 An exemplary flowchart is provided of one possible method among many possible methods of treating a fiber furnish with polymer A and B and ECA, the fiber furnish preferably consisting primarily of virgin or kraft fibers and optionally containing recycled or broke fibers; and / or process water in papermaking or papermboard manufacturing as described herein.

[0093] Description

[0094] The present invention provides a papermaking method that provides enhanced fixation and retention of ECA to fibers during papermaking, as well as retention of ECA to the produced paper or papermboard material, the method comprising separately adding a high - charge low - molecular - weight fast - inverting polymer for fixation (“fixation polymer”), an anionic ECA product, and a relatively low - charge high - molecular - weight fast - inverting polymer for retention (“retention polymer”), preferably in this order of addition. As previously discussed, the initially added high - fixation polymer enhances the fixation of the anionic ECA product and other anionic colloidal particles to anionic fibers, and the subsequently added retention polymer improves the retention of ECA, fines, and other colloidal particles in the web.

[0095] Also, surprisingly, a synergistic effect was found when two cationic fast - inverting polymers were used together with ECA in the same furnish. In particular, the combined use of two cationic fast - inverting polymers with ECA results in a synergistic enhancement of the drainage rate, retention of ECA to the fiber web, and retention of ECA, fines, and fibers on the paper produced using this synergistic combination. As shown by the examples, papermachine trials confirmed the synergistic effect of using two cationic fast - inverting polymers on the drainage rate and retention of ECA, fines, and fibers on paper.

[0096] The high-charge rapid inverse fixed polymer is a Q9 (cationic) and acrylamide copolymer containing 30 mol% to 40 mol% of Q9 monomer. The copolymer has a standard viscosity (SV) between 1.7 cps and 2.0 cps.

[0097] In an exemplary embodiment, the ultra-low SV value range and 3-D structure of the polyacrylamide of the copolymer are achieved using sodium hypophosphite as a chain transfer agent and methylene bisacrylamide as a crosslinking agent. The molecular weight of the cationic polymer is thereby reduced to a range suitable for improving fixation at increased polymer dosage levels without compromising paper formation.

[0098] The high Mw rapid inverse cationic retention polymer is a Q9 (cationic) and acrylamide copolymer containing 20 mol% to 30 mol% of Q9 monomer. The copolymer has a standard viscosity (SV) between 3.0 cps and 3.5 cps. It has been found that the optimal Mw range and 3-D polymer structure of the cationic polymer interact more effectively with colloids and fines than linear and conventional high Mw cationic polymers (typical SV range = 4.5 cps to 5.5 cps), and ultimately enhance the total retention of ECA, fines, and fibers on the paper machine.

[0099] It has been found that the combination of these two polymers has a synergistic effect on paper machine drainage and the total first-pass retention of ECA on ECA-enhanced paper grades. Additionally, this combination of copolymers provides additional benefits, including reduced dye and filler usage and improved dryer efficiency.

[0100] The advantages and exemplary embodiments of the present invention are further disclosed in detail below. Detailed Description

[0101] Before describing the present invention in detail, the following definitions are provided. Unless otherwise specified, those skilled in the art will interpret all terms.

[0102] Definitions

[0103] As used herein, the singular forms "a", "an", and "the" may mean "one", but also include plural referents such as "one or more" and "at least one", unless the context clearly dictates otherwise. All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise expressly stated.

[0104] As used herein, the term "or" in the claims means "and / or", unless expressly stated otherwise to refer only to alternatives or where the alternatives are mutually exclusive, although the present disclosure supports definitions that refer only to alternatives as well as "and / or".

[0105] As used herein, the term "or combinations thereof" refers to all permutations and combinations of the items listed before that term, unless otherwise specified.

[0106] As used herein, acrylamide or "AM" refers to a neutral monomer having the formula C3H5NO and a molecular weight of 71.08 g / mol.

[0107] As used herein, the term "amphoteric polymer" refers to a polymer containing both anionic and cationic groups on the macromolecular chain. These polymers exhibit both attraction and repulsion in their electrostatic intermolecular interactions (resulting in anti-polyelectrolyte association known as the "amphoteric effect"), and they exhibit excellent salt tolerance, especially in high Ca+2 aqueous compositions.

[0108] As used herein, the term "anionic monomer" can refer to any anionic monomer that is substantially all or partially (in equilibrium) anionic at a pH in the range of about 4.0 to about 9.0. An "anionic monomer" can be neutral at low pH (pH of about 2 to about 6) and can be anionic at low pH. Non-limiting representative anionic monomers include acrylic acid, sodium acrylate, ammonium acrylate, methacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid (AMPS), vinylsulfonic acid, styrenesulfonic acid, maleic acid, 3-sulfopropyl acrylate or 3-sulfopropyl methacrylate, or other water-soluble forms of these or other polymerizable carboxylic or sulfonic acids, sulfomethylated acrylamide, allyl sulfonate, itaconic acid, acrylamidomethylbutyric acid, fumaric acid, vinylphosphonic acid, allylphosphonic acid, phosphonomethylated acrylamide, methacrylate, itaconate, 2-acrylamido-2-methylpropanesulfonate, sulfoalkyl(meth)acrylic acid, sulfonated styrene, unsaturated dicarboxylic acids, sulfoalkyl(meth)acrylamide, vinyl acetate, n-vinylformamide, n-vinylacetamide, n-vinylcaprolactam, n-vinylimidazole, n-vinylpyridine, n-vinylpyrrolidone, acrylamidopropyltrimethylammonium chloride, salts of said acids, etc., or other anionic ethylenically unsaturated compounds.

[0109] As used herein, the term "breaking length" refers to a measure of the tensile strength of paper; theoretically, it is the maximum length at which a strip of paper can support itself without stretching and failing.

[0110] As used herein, the term "break of the web" generally refers to the breakage of paper during papermaking. "Dry-end breaks" can be caused by: (a) weak spots or holes in the paper, (b) insufficient elongation capacity relative to the tensile forces applied to the paper, (c) air handling and flutter problems, or (d) adhesion of the web to sticky surfaces. "Size-press breaks" can be caused by holes or weak areas in the paper, but they are also generally associated with internal sizing problems. "Wet-end breaks" are breaks of the wet web after the couch roll or in the wet press section of a paper machine. This can be caused by mechanical properties of the web such as wet web tensile strength and elongation. The ability of the wet web to resist breakage is a function of both tensile strength and elongation, and both of these variables are affected by the moisture content. A common way to increase the wet web tensile strength is to increase the softwood content in the furnish. Surfactants and other materials that tend to lubricate the contact between fibers tend to weaken the wet web. Other factors that can cause wet-end breaks include the deposition of sticky materials onto the press felts and transfer rolls in the wet press section, which can cause the paper to adhere excessively in these areas.

[0111] As used herein, the term "cationic monomer" generally refers to a monomer having a positive charge. Examples thereof include acryloyloxyethyl trimethyl ammonium chloride (Q9) monomers.

[0112] As used herein, a "chain transfer agent" is a compound used during polymerization that serves to control the molecular weight of the polymer. Examples of chain transfer agents that can be used in the production of acrylic-based polymers include sodium phosphite, sodium hypophosphite, sodium bisulfite, mercaptoacetic acid, mercaptopropionic acid, 2-propanethiol, 2-mercaptoethanol, benzenethiol, isopropyl alcohol, etc., with sodium hypophosphite or isopropyl alcohol being preferred.

[0113] As used herein, a "closed water system" refers to a papermaking process in which the amount of liquid effluent has been reduced, sometimes to zero (fully closed).

[0114] As used herein, the term "DCS" generally refers to dissolved and colloidal substances, which are typically derived from wood and typically have a negative charge and tend to interfere with retention aids and other papermaking additives.

[0115] As used herein, the term "dry strength" generally refers to the force or energy required to break a paper sample by one of various procedures after equilibration in a standard atmosphere.

[0116] As used herein, the term "dispersion" or "aqueous dispersion" generally refers to a heterogeneous mixture of a fluid (such as water) containing solid particles, where the solid particles form a phase-separated mixture in which one substance in the form of macroscopically or microscopically dispersed insoluble or soluble particles is suspended throughout another substance (usually a liquid substance). A dispersion has a dispersed phase (suspended particles) and a continuous phase (suspension medium) resulting from phase separation. Macroscopic particles usually separate and settle rapidly, while colloids usually do not settle completely or take a long time to completely settle into two separate layers.

[0117] As used herein, the term "emulsion polymer" generally refers to an inverse emulsion (water-in-oil) in which water droplets containing a polymer are suspended in an oil phase, also referred to as a hydrophobic phase.

[0118] As used herein, the term "fixative" generally refers to an additive that usually has a tendency to help hold a dye or other material onto the surface of a fiber due to a strong positive charge. This particularly includes cationic polymers.

[0119] As used herein, the term "furnish" generally refers to a mixture of cellulose fibers, optional fillers, and water for making paper.

[0120] As used herein, the term "flocculation" generally refers to the tendency of fibers to aggregate together in bundles in the presence of flow and especially in the presence of a retention aid; this term also refers to the action of a high-quality polymer forming bridges between suspended colloidal particles, thereby causing strong and relatively irreversible agglomeration.

[0121] As used herein, the term "internal sizing" generally refers to the treatment of a fiber furnish such that the paper will resist fluids.

[0122] As used herein, the term "inverse emulsion" refers to a liquid polymer composition of a polymer dissolved in an aqueous solution, which liquid polymer composition is dispersed into an oil phase (e.g., a hydrophobic liquid) to form an oil-continuous phase, and then mixed with the aqueous solution such that the dispersed polymer phase of the liquid polymer composition becomes substantially water-continuous and the hydrophobic liquid phase becomes the dispersed discontinuous phase. The inverse point can be characterized as the point at which the viscosity of the inverse polymer solution substantially reaches its maximum value under a given set of conditions. In practice, this can be determined, for example, by periodically measuring the viscosity of the composition over time, and when the results of three consecutive measurements are within the error criteria of the measurements, the solution is considered to be inverse.

[0123] As used herein, "kraft fiber" refers to cellulose fibers obtained by the kraft process (also known as kraft pulping or sulfate process) of converting wood into wood pulp, which cellulose fibers consist of almost pure cellulose fibers (the main component of paper).

[0124] As used herein, the term "lignocellulosic substrate" refers to paper and / or cardboard products formed from dry plant matter from any source, virgin or recycled, which can be coated, printed, and / or formed into packaging products. For example, such substrates include paper products made from pulp, such as those made by a process including forming an aqueous cellulose papermaking furnish, draining the furnish to form a sheet of paper, and drying the sheet of paper. The steps of forming the papermaking furnish, draining, and drying can be carried out in any conventional manner commonly known in the art. The substrate can contain polymer strengtheners, such as wet strength agents and dry strength agents. As previously mentioned, the feedstock containing the lignocellulosic substrate used in the present invention will preferably consist mainly or only of virgin fibers or kraft fibers.

[0125] As used herein, the term "liquid polymer" refers to a combination of at least one polymer and a liquid, which is typically an aqueous liquid. The polymer therein can be completely dissolved, or can be a partially dissolved suspension, dispersion, or slurry. An "aqueous polymer mixture" or "hydrated polymer composition" refers to a combination of at least one polymer and an aqueous liquid. When a dry polymer is mixed with an aqueous liquid, the polymer is initially partially hydrated at the polymer-water interface. The polymer does not immediately dissolve in an aqueous or non-aqueous solvent. Dissolution is controlled by the unraveling of the polymer chains or by the diffusion of the chains through the boundary layer adjacent to the polymer-solvent interface. After sufficient mixing, the polymer can become fully hydrated, at which point the wetting process is complete, and the polymer can be partially or fully dissolved, depending on the nature and composition of the polymer and the solvent.

[0126] As used herein, the term "monomer" generally refers to nonionic monomers, anionic monomers, cationic monomers, zwitterionic monomers, betaine monomers, and zwitterionic pair monomers.

[0127] As used herein, the term "nonionic monomer" generally refers to monomers having a neutral charge. Non-limiting examples of nonionic monomers include acrylamide, N-alkylacrylamide, N,N-dialkylacrylamide, methacrylamide, N-vinylmethylacetamide or formamide, vinyl acetate, vinylpyrrolidone, alkyl methacrylates, acrylonitrile, N-vinylpyrrolidone other acrylic (or other ethylenically unsaturated) esters or other water-insoluble vinyl monomers such as styrene or acrylonitrile. In this context, "nonionic monomer" generally refers to acrylamide.

[0128] As used herein, the term "OCC" refers to old corrugated cardboard boxes. Corrugated refers to those boxes in which the material is made of three layers of independent paper, two liners, and a layer of corrugated or wavy material sandwiched between them. OCC is commonly accepted for recycling of brown paper bags.

[0129] As used herein, the terms "paper-making process" and "paper-making application" generally refer to any process that can produce paper and / or paperboard products in any form. For example, such processes include the manufacture of paper products from pulp, such as methods including forming an aqueous cellulose paper-making furnish, draining the furnish to form paper, and drying the paper. The steps of forming the paper-making furnish, draining, and drying can be carried out in any conventional manner commonly known in the art. In some cases, the paper-making process and application can include the use of one or more polymer solutions, where the polymer solution can contain one or more DPAMs, one or more CDPAMs, one or more ADPAMs, and / or one or more PAE resins, for example as paper strengthening agents and / or wet strength agents.

[0130] As used herein, the term "paper-making system" generally refers to all equipment used to convert pulp into paper, paperboard, or market pulp, including raw material storage and preparation systems, paper or paperboard machines, and paper machine white water systems, broke recovery systems, and systems related to calendering, drying, on-machine coating, slitting, winding, and cutting fluids, as well as the materials and fluids used therein, such as additives, polymers, fibrous materials, one or more polymer solutions, where the polymer solution can contain one or more DPAMs, one or more CDPAMs, one or more ADPAMs, and / or one or more PAE resins, for example as paper strengthening agents and / or wet strength agents, etc.

[0131] As used herein, the term "polyacrylamide" or "PAM" generally refers to polymers and copolymers containing acrylamide moieties, and the term encompasses any polymer or copolymer containing acrylamide moieties, such as one or more acrylamide (co)polymers. In some cases, PAM can include anionic PAM (APAM), cationic PAMs (CPAM), and / or sulfonated PAM (SPAM).

[0132] As used herein, the terms "a polymer", "polymers", "polymeric", and like terms are used in their ordinary sense as understood by one of ordinary skill in the art, and thus may be used herein to refer to or describe macromolecules (or groups of such molecules) that include repeating units. Polymers can be formed in various ways, including by polymerizing monomers and / or by chemically modifying one or more of the repeating units of a precursor polymer. Unless otherwise specified, polymers can include "homopolymers", which can include substantially identical repeating units that can be formed by various methods (e.g., by polymerizing a particular monomer). Unless otherwise specified, polymers can also include "copolymers", which can include two or more different repeating units that can be formed, for example, by copolymerizing two or more different monomers and / or by chemically modifying one or more of the repeating units of a precursor polymer. Unless otherwise specified, polymers or copolymers can also include "terpolymers", which can include polymers that can include three or more different repeating units. As used herein, the term "polymer" is intended to include the acid form of the polymer and its various salts. In particular, the term "polymer" includes zwitterionic polymers, i.e., polymers that typically contain both anionic and cationic substituents in different molar ratios.

[0133] As used herein, the term "polymerization initiator" includes compounds and compositions that promote polymerization during, for example, acrylamide polymerization. Examples of polymerization initiators include 2,3-dimethyl-2,3-diphenylbutane, tert-butyl hydroperoxide, tert-amyl hydroperoxide, cumene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, hydrogen peroxide, cumyl isopropyl hydroperoxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hex-3-yne, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane, di(tert-butyl) peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di(tert-butylperoxyisopropyl)benzene, tert-butyl cumyl peroxide, di(tert-amyl) peroxide, dicumyl peroxide, butyl 4,4-di(tert-butylperoxy)valerate, tert-butyl peroxybenzoate, 2,2-di(tert-butylperoxy)butane, tert-amyl peroxybenzoate, tert-butyl peroxyacetate, tert-butyl peroxy(2-ethylhexyl) carbonate, tert-butyl peroxyisopropyl carbonate, tert-butyl peroxy-3,5,5-trimethylhexanoate, 1,1-di(tert-butylperoxy)cyclohexane, tert-amyl peroxyacetate, tert-amyl peroxy(2-ethylhexyl) carbonate, 1,1-di(tert-butylperoxy)-3,5,5-trimethylcyclohexane, 1,1-di(tert-amylperoxy)cyclohexane, tert-butyl monoperoxymaleate, 1,1'-azobis(hexahydrobenzonitrile), tert-butyl peroxyisobutyrate, tert-butyl peroxy-2-ethylhexanoate, benzoyl peroxide, tert-amyl peroxy-2-ethylhexanoate, di(4-methylbenzoyl) peroxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, ammonium persulfate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(isobutyronitrile), dilauroyl peroxide, dibenzoyl peroxide, di(3,5,5-trimethylhexanoyl) peroxide, tert-amyl peroxypivalate, tert-butyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxypivalate, tert-butyl peroxypivalate, dicetyl peroxydicarbonate, dimyristyl peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, di(4-tert-butylcyclohexyl) peroxydicarbonate, diisopropyl peroxydicarbonate, tert-butyl peroxypivalate, di-sec-butyl peroxydicarbonate, tert-amyl peroxypivalate, cumyl peroxyneodecanoate, di(3-methoxybutyl) peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxypivalate, cumyl peroxypivalate, and diisobutyryl peroxide. In an exemplary polymerization method, tert-butyl hydroperoxide is used as the initiator.

[0134] As used herein, "Q9 monomer" refers to 2-[(acryloyloxy)ethyl]trimethylammonium chloride (Q9), which has C8H16 The molecular formula of ClNO2 and a molecular weight of 193.67 g / mol.

[0135] As used herein, the term "recycled fiber" includes, for example, post-consumer recycled materials and pre-consumer recycled materials. Post-consumer recycled materials include materials recovered from consumer or commercial products that have been used by individuals, households, or as end-users of products by commercial, industrial, and institutional facilities for their intended purposes. Pre-consumer recycled materials include materials recovered from processes in secondary manufacturing or more downstream industries, where the material has not been intentionally produced, is not suitable for end-use, and cannot be reused in-situ in the same manufacturing process that generated the material. In particular, the term "recycled fiber" includes recycled fibers derived from processed paper and other consumer cellulose materials such as paper, old corrugated container board (OCC), mixed office waste (MOW), old magazines (OMG), unbleached kraft pulp, neutral sulfite semi-chemical (NCCS) pulp, and / or mechanical pulp. Additionally, the term "recycled fiber" includes the fiber fraction or broke of a paper machine, such as a paper machine that produces paper partially or entirely from recycled fibers, as well as actual post-consumer waste paper and cardboard. In some cases, recycled fibers can be recycled multiple times, such as 2, 3, 4, 5, 6, 7, or more times.

[0136] As used herein, the term "rheology modifier" refers to any substance that can change the rheological properties (e.g., resistance to deformation and flow) of a material. They are added to formulations to increase or decrease viscosity and control the final properties and characteristics of a liquid composition in a desired manner.

[0137] As used herein, the term "standard viscosity" or "SV" is used to indicate the molecular weight of a polymer with a relatively high molecular weight. Standard viscosity (SV) is measured using a Brookfield LVT-type viscometer equipped with a UL adapter (0.1 wt% polymer, in a 1M sodium chloride brine solution), where the spindle of the UL adapter rotates at 60 rpm. SV values are given for the inverse polymers disclosed herein because the term "Mw" in conventional molecular weights such as g / mol is generally inaccurate for high weight emulsion polymers.

[0138] As used herein, the term "stickies" refers to sticky materials that are typically included in recycled papermaking pulp and are usually associated with pressure-sensitive labels. Because they are deformable, they cannot be completely excluded by a pressure screen. The main culprits for stickies are polyvinyl acetate (PVA) and other adhesives in "pressure-sensitive" labels, which have become so common in mail and packaging that they can stick together and tend to accumulate in clumps or strings, adhere to papermaking equipment, fill felts, and / or form spots in paper products.

[0139] As used herein, the term "surface sizing" generally refers to the application of a solution, typically containing starch, to the surface of paper, usually to increase surface strength and sometimes to add a hydrophobic polymer or other material at the paper surface.

[0140] As used herein, the term "surfactant" refers to a surfactant typically composed of molecules having hydrophilic and hydrophobic groups and is used for wetting, emulsification, etc.

[0141] As used herein, the term "thick stock" generally refers to a mixture of papermaking pulp and other materials having a consistency of about 2% to 5%.

[0142] As used herein, the term "thin stock" generally refers to a mixture of papermaking pulp and other materials that has been diluted with white water at a fan pump.

[0143] As used herein, the term "wet strength" generally refers to the strength of a paper after it has been exposed to a standard solution for a standard length of time, but is usually expressed as a ratio to the dry strength.

[0144] As used herein, the term "wet end of a paper machine" generally refers to the part of the papermaking process between pulping (or bleaching) and wet pressing of the paper.

[0145] As used herein, the term "white water" generally refers to process water within a paper machine system, particularly the water discharged from the paper during paper formation.

[0146] As used herein, the term kg / T means kilograms per metric ton.

[0147] Detailed description

[0148] The present invention relates to a papermaking method that includes separately adding a high-charge low-molecular-weight fast-inverting polymer for fixation, an anionic ECA product, and a relatively low-charge high-molecular-weight fast-inverting polymer for retention, with the preferred addition order being this sequence.

[0149] It is hypothesized that the high-cationic charged fast-inverting fixation polymer enhances the fixation of the anionic ECA product and other anionic colloidal particles to anionic fibers; and the high-Mw fast-inverting cationic retention polymer added subsequently (after ECA) improves the retention of ECA, fines, and other colloidal particles in the web.

[0150] As disclosed earlier, when two cationic fast-inverting polymers are used together with ECA in the same furnish (but added separately), synergistic benefits are obtained. In particular, the combined use of the two cationic fast-inverting polymers with ECA synergistically enhances the overall retention of ECA, fines, and fibers on the paper machine.

[0151] In addition, the combination of these two polymers causes a synergistic effect on improving the drainage of the paper machine and on the overall first-pass retention of ECA on ECA-reinforced paper grades.

[0152] Also additionally, the combination of these two polymers allows for the use of reduced amounts of dyes and other fillers.

[0153] Furthermore, the combination of these two polymers synergistically improves dryer efficiency.

[0154] In fact, as disclosed below, paper machine trials have confirmed the synergistic effect of using two cationic fast-inverting polymers on the retention of ECA, fines, and fibers on paper.

[0155] The materials, preparation methods, and their use in the method of the present invention are further described below.

[0156] The immobilized polymer of the present invention

[0157] The high-charge fast-inverting fixed polymer used in the method of the present invention is a Q9 (cationic) and acrylamide copolymer having 30 mol% to 40 mol% of Q9 monomers. The copolymer has a standard viscosity (SV) between 1.7 cps and 2.0 cps. The ultra-low SV value range and 3-D structure of polyacrylamide in the copolymer were achieved using sodium hypophosphite as a chain transfer agent and methylene bisacrylamide as a crosslinking agent in an exemplary embodiment (as described in the inverse emulsion method below). The molecular weight of the cationic polymer was reduced to a range suitable for improving fixation without compromising paper formation at increased polymer dosage levels.

[0158] This high-charge fast-inverting fixed polymer has been shown to be more effective in fixation than conventional charge fixation / control agents (CCAs) such as polyacrylamide-DADMAC dispersions, polyamines, and poly-DADMAC solution polymers. The polymer is typically synthesized in emulsion form, i.e., by using the inverse emulsion method described below.

[0159] The retention polymer of the present invention

[0160] The high Mw fast inverse cationic retention polymer used in the method of the present invention is a copolymer of Q9 (cationic) and acrylamide, which has 20 mol% to 30 mol% of Q9 monomers. The copolymer has a standard viscosity (SV) between 3.0 cps and 3.5 cps. It has been found that the optimal Mw range and 3-D polymer structure of this cationic polymer interact more effectively with colloids and fines than linear and conventional high Mw cationic polymers (typical SV range = 4.5 cps - 5.5 cps), and thereby enhance the total retention of ECA, fines, and fibers on the paper machine. In the exemplary embodiments disclosed below, the polymer is generally synthesized in emulsion form, i.e., by using the inverse emulsion method.

[0161] Synthesis of the rapid reversed-phase retention polymer and the immobilized polymer of the present invention

[0162] The subject retention polymer and fixing polymer of the present invention in the exemplary embodiments are synthesized in emulsion form by using the inverse emulsion method generally described below.

[0163] Preparation of the monomer phase:

[0164] For the immobilized polymer : A 70 / 30 acrylamide / Q9 molar ratio, 5 ppm to 15 ppm of methylene bisacrylamide as a crosslinking agent, 300 ppm to 400 ppm of sodium hypophosphite as a chain transfer agent, addition of 4% to 5% of a citric acid solution and 0.08% of diethylenetriaminepentaacetic acid, and adjusting the pH of the monomer phase to be between 3.3 and 3.7 with sodium hydroxide. During these processes, the temperature of the reactants is ideally maintained below 30 °C, optionally by using an ice bath.

[0165] For the retention polymer : An 80 / 20 acrylamide / Q9 molar ratio, 2 ppm to 10 ppm of methylene bisacrylamide as a crosslinking agent, 50 ppm to 80 ppm of sodium hypophosphite as a chain transfer agent, addition of 4% to 5% of a citric acid solution and 0.08% of diethylenetriaminepentaacetic acid, and adjusting the pH of the monomer phase to be between 3.3 and 3.7 with sodium hydroxide. During these processes, the temperature of the reactants is ideally maintained below 30 °C, optionally by using an ice bath.

[0166] Preparation of the oil phase: (Same for both emulsion polymers)

[0167] Add 20 wt% to 22 wt% of a petroleum solvent to a container (optionally a peeled 1000 mL steel can) and stir, optionally using an overhead mixer. If paper is to be produced using a "green" method, add a hydrophobic solvent, optionally 2 wt% to 3 wt% of an ethoxylated alcohol (C10 - C16, C12 - C16, C12 - C14) or a vegetable oil or other naturally occurring oil. Mix it, optionally for at least 10 minutes.

[0168] Add the monomer phase to the oil phase:

[0169] a) Slowly add the monomer solution to the oil phase, optionally over a 30 - second period, and mix the blend, optionally for about 20 minutes. Record the viscosity and homogenize the mixture. Record the viscosity again after homogenization. Pour the mixture into a polymerization reactor and record the initial temperature.

[0170] b) Bubble nitrogen through the contents of the reactor, optionally for about 1 hour and stir continuously.

[0171] Polymerization:

[0172] After bubbling for 1 hour, add a polymerization initiator to the mixture, optionally tert - butyl hydroperoxide, further optionally at 20 ppm to 40 ppm, and mix the blend, optionally for about 10 minutes. Introduce SO2 gas (0.4%), optionally at 18 SCCM, and monitor the temperature as the reaction proceeds. Observe an exotherm (indicated by an increase in temperature) and signal polymerization. Control the flow rate of SO2 such that the increase in temperature is gradual (optionally about 1.5 °C / min or about 1 °C / min). To obtain a polymer of the desired molecular weight, it is desirable to keep the temperature below 50 °C, optionally using a water bath and maintaining it by simultaneously cutting off the SO2 supply. When no further increase in temperature is observed, even when SO2 is fed continuously, it indicates that polymerization is complete. At this point, set the SO2 flow rate back to the initial value, and set the reactor temperature back to 50 °C and hold for about 1.5 hours. It is desirable to continuously bubble nitrogen throughout the process.

[0173] Post - additives:

[0174] Add a demulsifier or reverse surfactant (optionally an ethoxylated alcohol) to the polymer, further optionally at an addition rate of about 2.0 wt%, and allow the blend to mix, optionally for about 20 minutes. Then allow the reactor to cool to <30 °C, and then transfer the polymer to a suitable container.

[0175] Exemplary engineered cellulose additives that can be used in the present invention

[0176] The engineered cellulose derivatives or additives according to the present invention refer to anionic cellulose derivatives having a net ionic group substitution degree of at most about 0.65, preferably about 0.05 to 0.55. The cellulose derivatives contain anionic groups selected from the group consisting of carboxylate, carboxyalkyl, sulfonate, sulfoalkyl, phosphate, and phosphonate groups and mixtures thereof. More specifically, the cellulose derivatives have a carboxyalkyl group substitution degree of at most about 0.65, preferably about 0.05 to 0.55. The anionic cellulose derivatives have a viscosity of an approximately 2 wt% aqueous solution that is greater than or equal to 100 mPa·s, preferably greater than or equal to 2500 mPa·s at 25 °C. The viscosity is optionally measured using a Brookfield LVT viscometer at 30 rpm with a #62 spindle.

[0177] Preferably, the cellulose derivatives are water-soluble or at least partially water-soluble or water-dispersible, more preferably water-soluble or at least partially water-soluble. Preferably, the cellulose derivatives are ionic. The cellulose derivatives can be anionic, cationic, or amphoteric, preferably anionic or amphoteric. Examples of suitable cellulose derivatives include cellulose ethers, such as anionic and amphoteric cellulose ethers, preferably anionic cellulose ethers. The cellulose derivatives preferably have ionic or charged groups or substituents. Examples of suitable ionic groups include anionic and cationic groups. Examples of suitable anionic groups include carboxylate, such as carboxyalkyl; sulfonate, such as sulfoalkyl; phosphate; and phosphonate groups, where the alkyl group can be methyl, ethyl, propyl, and mixtures thereof, suitably methyl; suitably, the cellulose derivatives contain anionic groups that include carboxylate groups, such as carboxyalkyl groups. The counterions of the anionic groups are typically alkali metals or alkaline earth metals, preferably sodium.

[0178] Examples of suitable cationic groups of the cellulose derivatives according to the present invention include salts of amines, suitably salts of tertiary amines, and quaternary ammonium groups, preferably quaternary ammonium groups. The substituents attached to the nitrogen atoms of the amines and quaternary ammonium groups may be the same or different and may be selected from alkyl, cycloalkyl, and alkoxyalkyl groups, and one, two, or more of the substituents may form a heterocycle together with the nitrogen atom. The substituents generally independently of one another include from 1 to about 24 carbon atoms, preferably from 1 to about 8 carbon atoms. The nitrogen of the cationic group may be attached to cellulose or its derivative by an atomic chain suitably comprising carbon and hydrogen atoms and optionally O and / or N atoms. Generally, the atomic chain is an alkylene group having from 2 to 18 and suitably 2 to 8 carbon atoms, which is optionally interrupted or substituted by one or more heteroatoms such as O or N, such as an alkyleneoxy group or a hydroxypropyl group. Preferred cellulose derivatives containing cationic groups include those obtained by reacting cellulose or its derivative with a quaternizing reagent selected from 2,3-epoxypropyltrimethylammonium chloride, 3-chloro-2-hydroxypropyltrimethylammonium chloride, and mixtures thereof.

[0179] The cellulose derivatives of the present invention may contain nonionic groups such as alkyl or hydroxyalkyl groups, for example hydroxymethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl, and mixtures thereof, such as hydroxyethylmethyl, hydroxypropylmethyl, hydroxybutylmethyl, hydroxyethylethyl, hydroxypropyl, etc. In a preferred embodiment of the present invention, the cellulose derivative contains both ionic and nonionic groups.

[0180] Examples of suitable cellulose derivatives according to the present invention include carboxyalkyl celluloses, such as carboxymethyl cellulose, carboxyethyl cellulose, carboxypropyl cellulose, sulfoethyl carboxymethyl cellulose, carboxymethyl hydroxyethyl cellulose (“CM-HEC”), carboxymethyl cellulose in which the cellulose is substituted by one or more nonionic substituents, preferably carboxymethyl cellulose (“CMC”). Examples of suitable cellulose derivatives and methods for their preparation include those disclosed in U.S. Patent No. 4,940,785, which is hereby incorporated by reference herein.

[0181] As used herein, the term "degree of substitution" or "DS" means the number of substituted ring sites of the β - anhydroglucose rings of a cellulose derivative. Since there are three hydroxyl groups available for substitution on each anhydroglucose ring of cellulose, the maximum value of DS is 3.0. According to a preferred embodiment of the present invention, the cellulose derivative has a net ionic group substitution degree ("DSNI") of at most about 0.65, i.e., the cellulose derivative has an average net ionic substitution degree of at most about 0.65 per glucose unit. The net ionic substitution can be net anionic, net cationic or net neutral substitution. When the net ionic substitution is net anionic substitution, there is a net excess of anionic groups (net anionic groups = the average number of anionic groups per glucose unit minus the average number of cationic groups (if any)), and DSNI is the same as the degree of substitution of the net anionic groups ("DSNA"). When the net ionic substitution is net cationic substitution, there is a net excess of cationic groups (net cationic groups = the average number of cationic groups per glucose unit minus the average number of anionic groups (if any)) and DSNI is the same as the degree of substitution of the net cationic groups ("DSNC"). When the net ionic substitution is net neutral substitution, the average number of anionic and cationic groups (if any) per glucose unit is the same, and DSNI as well as DSNA and DSNC are 0. According to another preferred embodiment of the present invention, the cellulose derivative has a carboxyalkyl substitution degree ("DSCA") of at most about 0.65, i.e., the cellulose derivative has an average carboxyalkyl substitution degree of at most about 0.65 per glucose unit. The carboxyalkyl group is suitably a carboxymethyl group, and then the DSCA referred to herein is the same as the degree of substitution of the carboxymethyl group ("DSCM"). According to these embodiments of the present invention, DSNI, DSNA, DSNC and DSCA are each independently generally at most about 0.60, preferably at most about 0.55, while DSNI, DSNA, DSNC and DSCA are each independently generally at least 0.01, suitably at least about 0.05, preferably at least about 0.10, more preferably at least about 0.15. The ranges of DSNI, DSNA, DSNC and DSCA are each independently generally from about 0.01 to about 0.60, preferably from about 0.05 to about 0.55.

[0182] Anionic or amphoteric cellulose derivatives generally have an anionic degree of substitution (“DSA”) in the range of from 0.01 to about 1.0, provided that DSNI and DSNA are as defined herein; suitably about 0.05, preferably about 0.10, and more preferably about 0.15, and suitably up to about 0.75, preferably up to about 0.55. Cationic or amphoteric cellulose derivatives can have a cationic degree of substitution (“DSC”) in the range of from 0.01 to about 1.0, provided that DSNI and DSNC are as defined herein; suitably about 0.02, preferably about 0.03, and more preferably about 0.05, and suitably up to about 0.75, preferably up to about 0.55. The cationic group is suitably a quaternary ammonium group, and then the DSC referred to herein is the same as the degree of substitution of the quaternary ammonium group (“DSQN”). For the amphoteric cellulose derivatives of the present invention, DSA or DSC can of course be higher than 0.65, provided that DSNA and DSNC are as defined herein, respectively. For example, if DSA is 0.75 and DSC is 0.15, then DSNA is 0.60.

[0183] Examples of suitable cellulose derivatives having a degree of substitution as defined above include water-soluble low DS carboxyalkyl cellulose derivatives. Based on the total weight of the dry cellulose derivative, the water-soluble cellulose derivative suitably has a solubility in aqueous solution of at least 85 wt%, preferably at least 90 wt%, more preferably at least 95 wt%, and most preferably at least 98 wt%. An exemplary preferred ECA is ECA 720.

[0184] It has been found that the fast inverse cationic polyacrylamide emulsions disclosed herein have excellent fixing and retention properties in pulp and paper systems. A synergistic effect can be seen when two cationic fast inverse polymers are used together in the same furnish.

[0185] As shown in an example of using a combination of two cationic fast inverse polymers with ECA during papermaking, where each is added separately to the papermaking system, i.e., adding the fixing polymer, then adding ECA, and then adding the retention polymer, provides separate and synergistic benefits, including one or more of the following:

[0186] (i) The high-charge fast inverse fixing polymer enhances the fixing of ECA to anionic fibers without disrupting paper formation, optionally at high polymer dosage levels;

[0187] (ii) The high-charge fast inverse fixing polymer promotes the fixing of anionic ECA products and other anionic colloidal particles to anionic fibers;

[0188] (iii) High-charge rapid inverse fixing polymers promote the fixing of ECA more effectively than traditional charge fixing / control agents (CCA) such as polyacrylamide-DADMAC dispersions, polyamines, and polyDADMAC solution polymers;

[0189] (iv) High molecular weight rapid inverse cationic retention polymers interact with colloids and fines more effectively than linear and conventional high Mw cationic polymers (typical SV range = 4.5 cPs to 5.5 cPs);

[0190] (v) High molecular weight rapid inverse cationic retention polymers enhance the total retention of ECA, fines, and fibers on the paper machine;

[0191] (vi) The combination of high-charge rapid inverse cationic fixing retention polymers and high molecular weight rapid inverse cationic retention polymers causes a synergistic effect on the drainage of the paper machine;

[0192] (vii) The combination of high-charge rapid inverse cationic fixing polymers and high molecular weight rapid inverse cationic retention polymers causes a synergistic effect on the total first-pass retention of engineered cellulose additives (ECA) on ECA-enhanced paper grades;

[0193] (viii) The combination of high-charge rapid inverse cationic fixing polymers and high molecular weight rapid inverse cationic retention polymers promotes dye retention during papermaking;

[0194] (ix) The combination of high-charge rapid inverse cationic fixing polymers and high molecular weight rapid inverse cationic retention polymers reduces the amount of dye required during papermaking;

[0195] (x) The combination of high-charge rapid inverse cationic fixing polymers and high molecular weight rapid inverse cationic retention polymers reduces the amount of filler required during papermaking;

[0196] (xi) The combination of high-charge rapid inverse cationic fixing polymers and high molecular weight rapid inverse cationic retention polymers improves dryer efficiency;

[0197] (xii) The combination of high-charge rapid inverse cationic fixing polymers and high molecular weight rapid inverse cationic retention polymers promotes the retention of dyes and / or fillers;

[0198] (xiii) The combination of high-charge rapid inverse cationic fixing polymers and high molecular weight rapid inverse cationic retention polymers reduces the amount of starch required;

[0199] (xiv) The combination of high-charge rapid inverse cationic fixing polymers and high molecular weight rapid inverse cationic retention polymers has a synergistic effect on the retention of ECA, fines, and fibers on the paper produced; or

[0200] (xv)Any of the foregoing combinations.

[0201] In some embodiments, the methods and polymer / ECA combinations of the present invention can be added to any process water from pulp, paper, or paperboard production and / or to the thick or thin stock used for pulp, paper, or paperboard production. Preferably, the stock mainly or only contains virgin fibers or kraft fibers, and optionally may contain some recycled fibers and / or broke fibers.

[0202] In an exemplary embodiment, the fiber stock contains at least 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt%, or 100 wt% of virgin fibers or kraft fibers, and may contain some recycled fibers, although the preferred use of the methods of the present invention is for treating stock containing virgin fibers or kraft fibers. In some cases, such fibers may contain starch, and in some cases, may contain a significant amount of starch.

[0203] In some embodiments, the treated fiber stock may contain some OCC recycled fibers, which may contain approximately 5% native sizing press starch and starch gels that can be recovered for use in the manufacture of paper or paperboard, the starch being derived from recycled fibers and / or broke fibers in the stock and / or added to the treated fiber stock. Generally, recycled fiber materials contain low molecular weight starch, which is derived from surface sizing of paper or paperboard and has poor retention on fibers because it is usually uncharged or has a slightly anionic charge.

[0204] The wet-end applications of the present invention include adding a fixing polymer, an ECA, and a retention polymer to the thick stock and / or thin stock. The thick stock is herein understood to be a fiber stock or furnish having a consistency above 1% (i.e., above 10 g dry solids / L of stock), and the thin stock has a consistency below 1% (i.e., below 10 g dry solids / L of stock).

[0205] These fiber stock fractions may optionally include increased amounts of low molecular weight (LMW) starch, hydrophobic agents, fines, fillers / pigments, dyes, etc. The thick or thin stock will again preferably mainly contain virgin fibers or kraft fibers, and optionally may contain some recycled fibers and / or broke fibers, which optionally are from different sources, such sources including, for example, recycled fiber materials and / or broke and / or coated broke.

[0206] According to some embodiments of the present invention, the treated fiber stock mainly containing kraft fibers or virgin fibers may optionally contain some fibers derived from recycled paper, old corrugated cartons (OCC), mixed office waste (MOW), old magazines (OMG), unbleached kraft pulp, neutral sulfite semi-chemical (NCCS) pulp, and / or mechanical pulp.

[0207] The treated fiber raw material that mainly or only contains virgin fibers or kraft fibers may contain variable amounts of colloidal fines, colloidal particles, fillers, hydrophobic and hydrophilic particles, depending on the fiber source and the papermill processing method. In addition, the fiber suspension is usually diluted with papermill white water, which also contains variable amounts of colloidal fines, etc. The furnish or fiber raw material used in the present invention may contain low levels of fines (e.g., the fines content ranges from 0.1% to 5% by dry fines mass / volume, more typically 0.1% to 0.2%) or high levels of fines (e.g., the fines content ranges from 5% to 15%). The definition of "fines" for the present application is any suspended particles smaller than a 125P filter (e.g., 0.76 microns or 200 mesh).

[0208] The retention polymer and the fixing polymer of the present invention can be in the form of a solution of the subject rapid inverse cationic retention polymer and fixing polymer, which can be used as a pumped product, optionally without the need for conventional polymer inversion and aging tanks. In contrast, conventional polyacrylamide emulsions, such as cationic retention aids with molecular mass values in the range of 10 MDa to 20 MDa and SV > 4.5 mPas, do not immediately invert in water at normal mixing speeds (<500 RPM), and the pre-diluted conventional polymer solution should be aged for at least 30 minutes before use.

[0209] The retention polymer and the fixing polymer can be synthesized off-site and delivered to the papermill, and then mixed on-site. Alternatively, the retention polymer and the fixing polymer can be pre-blended off-site before reaching the papermill, and then delivered to the customer site as a pre-blended emulsion polymer. On-site mixing is flexible, allowing for easy customization of the blending ratio to meet the specific process water and other requirements of the mill. In some embodiments, the retention and fixing rapid inverse polymer solution can be produced by injecting the emulsion into a high-shear water pump and optionally inverting the mixture via a static mixer before pumping the polymer solution onto the paper machine.

[0210] When the fixing polymer is used in combination with the optimal amount of the retention polymer (i.e., in the optimal ratio), an increased synergistic effect of the combination of the present invention can be observed. The retention polymer has a higher molecular weight than the fixing polymer and has been found to be more effective in mechanical retention; i.e., the retention polymer is better at bridging fiber to fiber. The fixing polymer has a lower molecular weight than the retention polymer and has been found to be more effective in fixing ECA to the fiber; i.e., it is a better fixative. Without being bound by theory, it can be inferred that the polymer combination in the optimal blending ratio provides optimal fixing of ECA and better mechanical retention, thus providing a possible mechanical rationale for the synergistic benefits of the combination.

[0211] The optimal ratio (mass ratio of retention / fixation polymer) depends on many variables including, but not limited to, the paper mill, the point of addition in the papermaking process, furnish characteristics (including pH, conductivity), and the content of starch, fines, sizing agent, ash, and / or dyes. The optimal ratio is determined empirically through preliminary studies for each specific mill on a furnish-by-furnish basis. In an exemplary embodiment, the ratio range of retention polymer to fixation polymer can be from about 90 / 10 to less than 1 / 99, and preferably in the range of 85 / 15 to 15 / 85. At the optimal ratio, the solution of the two polymers causes a synergistic or additive increase in ECA retention compared to the application of an equal dosage level of either the retention or fixation polymer alone.

[0212] In some exemplary embodiments, the present invention provides a method for treating starch-containing furnish and / or broke fibers and / or process water in paper or board manufacturing using a retention polymer and a fixation polymer. In a preferred embodiment, the treatment is carried out prior to using the treated furnish in a papermaking process or other industrial process using a cationic functional polymer or other papermaking chemicals.

[0213] The retention polymer and the fixation polymer can be separately injected into the process stream at several points in the manufacturing process, including but not limited to chemical addition point 1 upstream of thickening, where the furnish has a consistency of less than about 10%, 5%, 2%, 1%, or 0.65% (i.e., the dry mass percentage in the furnish) (see Figure 4 ). Adding an inverse solution of a cationic polymer to the fiber suspension prior to the thickening step is advantageous as it effectively prevents the enrichment of ECA in the water cycle in most processes and a large amount of ECA is effectively retained on the fibers.

[0214] The retention polymer and the fixation polymer can also be added at chemical addition point 2 upstream of forming and / or pressing and / or drying (see Figure 4 ), where the furnish has a consistency of about 10% to 30% (i.e., the dry mass percentage in the furnish). The method of the present invention is practiced to capture and retain ECA that would otherwise be lost or degraded, thereby protecting the ECA for incorporation into the paper or board. The optimal ratio for each paper mill and furnish composition is determined empirically to cause a synergistic or additive increase in ECA retention without over-flocculating the fibers or forming hydrophobic substances such as stickies or flocs in the furnish.

[0215] The solution of the retention polymer and the fixing polymer can also be added to the fiber suspension before washing and / or cleaning the fiber suspension to improve the ECA retention and filtration of the fiber suspension, where a cleaner filtrate can be obtained, as well as a higher content of fines in the fiber suspension with which sizing agents, fillers, dyes, etc. can associate. The solution of the retention polymer and the fixing polymer can also be added separately to the fiber suspension before the machine chest of a paper machine or a board machine or before the furnish chest.

[0216] Due to the high polymer molecular weight of conventional retention aid polymers, their dosage levels are generally limited to less than 0.45 kg / t (where kg / t represents the dry polymer mass per ton of process pulp), and are generally limited to less than 0.3 kg / t so as not to overflocculate the fiber furnish at the wet end. In contrast, for the present invention, the solution of the fast-inverting retention polymer and the fixing polymer can be added to the fiber furnish and / or broke fibers in the mill and / or process water in the manufacture of paper or board at a dosage level range of 0.25 kg / t to 5 kg / t, preferably 0.3 kg / t to 1.0 kg / t, and more preferably 0.5 kg / t to 0.7 kg / t. The optimal dosage level for mill applications will depend on the paper mill, fiber and furnish characteristics, consistency, addition point, and the ratio of the retention polymer to the fixing polymer. The retention polymer and the fixing polymer of the present invention provide a wide dosage range for increasing the fixation and retention of ECA without overflocculating or disrupting the formation of the paper.

[0217] A preferred embodiment of the present invention provides a fiber furnish that comprises a high content of virgin fibers or kraft fibers, preferably at least 50 wt%, preferably at least 60 wt%, more preferably at least 70 wt%, or even more preferably at least 80 wt% or 100 wt% of kraft fibers or virgin fibers, optionally containing a lesser amount of recycled fibers and / or broke fibers in the mill, such as up to 5 wt% to 10 wt%, optionally a starch-containing furnish, optionally starch-containing process water from pulp, paper, or board production, and the fiber furnish comprises the retention polymer and the fixing polymer according to any one of the foregoing and ECA and / or has been treated with the retention polymer and the fixing polymer and ECA.

[0218] The paper made by the method according to the present invention can be any kind of paper or board and can optionally contain some recycled fiber material and / or broke and / or coated broke, such as up to 5 wt% to 10 wt%.

[0219] Exemplary embodiments

[0220] A. A papermaking method, which includes adding an engineered cellulose additive (ECA), optionally to replace virgin fibers and / or starch and / or as a strength enhancer, wherein the papermaking method includes using the following:

[0221] (i) A high-charge rapid-inversion fixed copolymer, which contains 2-(acryloyloxy)ethyl]trimethylammonium chloride (Q9) (cationic) and acrylamide monomers ("fixed polymer");

[0222] (ii) An anionic ECA; and

[0223] (iii) A high molecular weight rapid-inversion cationic retention polymer, which contains Q9 (cationic) and acrylamide monomers ("retention polymer");

[0224] wherein each is added separately to the papermaking system.

[0225] B. A method for treating fibrous raw materials and / or process water used in pulp, paper, or paperboard production, the fibrous raw materials and / or process water preferably mainly containing kraft fibers or virgin fibers, the method including obtaining the fibrous raw materials and / or process water, and treating the fibrous raw materials and / or process water with the following:

[0226] (i) A high-charge rapid-inversion fixed copolymer, which contains Q9 (cationic) and acrylamide monomers ("fixed polymer");

[0227] (ii) An anionic ECA; and

[0228] (iii) A high molecular weight rapid-inversion cationic retention polymer, which contains Q9 (cationic) and acrylamide monomers ("retention polymer");

[0229] wherein each is added separately to the fibrous raw materials and / or process water.

[0230] C. A method for manufacturing paper or paperboard, wherein a fibrous web is formed from an aqueous suspension of fibers, the method including:

[0231] - Providing an aqueous fiber suspension, which preferably mainly contains kraft fibers or virgin fibers, and optionally contains recycled fiber material and / or coated broke,

[0232] - Optionally diluting the aqueous fiber suspension,

[0233] - Delivering the aqueous fiber suspension to a headbox, draining the aqueous fiber suspension on a wire screen to form a wet fibrous web, and

[0234] - pressing and drying the wet fibrous web to obtain a web of paper or paperboard, the process comprising separately adding (i) a high charge fast reverse phase fixation copolymer comprising Q9 (cationic) and acrylamide monomers, (ii) ECA, and (iii) a high molecular weight fast reverse phase cationic retention polymer comprising Q9 (cationic) and acrylamide monomers, wherein each of (i) (ii) and (iii) is separately added during manufacturing.

[0235] D. The method of embodiment A, B or C, wherein the high charge fast reverse phase fixation copolymer (fixation polymer) promotes the fixation of the ECA and optionally other colloidal particles to the anionic fibers, and / or the high molecular weight fast reverse phase cationic polymer (retention polymer) promotes the retention of ECA and optionally fines and other colloidal particles in the fibrous web.

[0236] E. The method of any preceding embodiment, wherein the high charge fast reverse phase immobilization polymer comprises 30 mol% to 40 mol% Q9 monomer and a standard viscosity (SV) between 1.7 cps and 2.0 cps.

[0237] F. The method of any preceding embodiment, wherein the high molecular weight fast reverse phase cationic retention copolymer comprises 20 mol% to 30 mol% Q9 monomer and has a standard viscosity (SV) between 3.0 cPs and 3.5 cPs.

[0238] G. The method according to any one of the preceding embodiments, wherein

[0239] (i) first adding the high-charge fast reverse phase fixing polymer to the papermaking system;

[0240] (ii) adding ECA to the papermaking system after adding the high charge fast phase reverse fixation polymer; and

[0241] (iii) After adding ECA to the papermaking system, adding the high molecular weight fast reverse phase cationic retention polymer.

[0242] H. The method of any preceding embodiment, wherein the combined dosage of the retention polymer and the fixation polymer is equal to or greater than the ECA.

[0243] I. The method of any one of the preceding embodiments, wherein the retention polymer is dosed in the range of 0.1 kg to 5 kg per ton.

[0244] J. The method of any preceding embodiment, wherein the dosage of the immobilizing polymer ranges from 0.1 kg to 5 kg per ton.

[0245] K. A method according to any one of the foregoing embodiments, wherein the combined dosage range of the fixing polymer and the retention polymer is from 0.2 kg to 5 kg per ton.

[0246] L. A method according to any one of the foregoing embodiments, wherein the dosage range of the ECA is from 0.2 kg to 5 kg per ton.

[0247] M. A method according to any one of the foregoing embodiments, wherein

[0248] (i) the interval between steps (i) and (ii) and (iii) is sufficient to achieve sufficient mixing, and according to the shear dynamics during mixing, the interval is typically at least 3 seconds to 5 minutes.

[0249] N. A method according to any one of the foregoing embodiments, which comprises one or more other additives commonly used in papermaking, such as dyes, starches, microbicides, other fixing agents or retention agents, sizing agents, etc.

[0250] O. A method according to any one of the foregoing embodiments, wherein

[0251] (i) the high-charge fast-inverting fixing polymer enhances the fixing of ECA to the anionic fibers without disrupting the formation of the paper, optionally at a high polymer dosage level;

[0252] (ii) the high-charge fast-inverting fixing polymer promotes the fixing of the anionic ECA product and other anionic colloidal particles to the anionic fibers;

[0253] (iii) the high-charge fast-inverting fixing polymer promotes the fixing of ECA more effectively than conventional charge fixing / control agents (CCA) such as CC610 (polyacrylamide-DADMAC dispersion), polyamines, and poly-DADMAC solution polymers;

[0254] (iv) the high-molecular-weight fast-inverting cationic retention polymer interacts more effectively with colloids and fines than linear and conventional high Mw cationic polymers (typical SV range = 4.5 cPs to 5.5 cPs);

[0255] (v) the high-molecular-weight fast-inverting cationic retention polymer enhances the total retention of the ECA, the fines, and the fibers on the paper machine;

[0256] (vi) the combination of the high-charge fast-inverting cationic fixing polymer and the high-molecular-weight fast-inverting cationic retention polymer causes a synergistic effect on the drainage of the paper machine;

[0257] (vii) The combination of the high-charge fast-inverting cationic fixing polymer and the high-molecular-weight fast-inverting cationic retention polymer causes a synergistic effect on the total first-pass retention of the engineered cellulose additive (ECA) on ECA-enhanced paper grades;

[0258] (viii) The combination of the high-charge fast-inverting cationic fixing polymer and the high-molecular-weight fast-inverting cationic retention polymer promotes dye retention;

[0259] (ix) The combination of the high-charge fast-inverting cationic fixing polymer and the high-molecular-weight fast-inverting cationic retention polymer reduces the amount of dye required;

[0260] (x) The combination of the high-charge fast-inverting cationic fixing polymer and the high-molecular-weight fast-inverting cationic retention polymer reduces the amount of filler required;

[0261] (xi) The combination of the high-charge fast-inverting cationic fixing polymer and the high-molecular-weight fast-inverting cationic retention polymer improves dryer efficiency;

[0262] (xii) The combination of the high-charge fast-inverting cationic fixing polymer and the high-molecular-weight fast-inverting cationic retention polymer promotes the retention of dyes and / or fillers;

[0263] (xiii) The combination of the high-charge fast-inverting cationic fixing polymer and the high-molecular-weight fast-inverting cationic retention polymer reduces the amount of starch required;

[0264] (xiv) The combination of the high-charge fast-inverting cationic fixing polymer and the high-molecular-weight fast-inverting cationic retention polymer has a synergistic effect on the retention of ECA, fines, and fibers on the paper produced; or

[0265] (xv) Any of the foregoing combinations.

[0266] P. The method according to any one of the foregoing embodiments, wherein the total dosage by weight of the high-charge fast-inverting cationic fixing polymer and the high-molecular-weight fast-inverting cationic retention polymer ranges from about 0.8 times to about 20 times the amount of the ECA added to the papermaking system, from about 1.0 times to about 10 times the amount of the ECA, from about 1.0 times to about 5.0 times the amount of the ECA, from about 1.0 times to about 3.0 times the amount of the ECA, from about 1.0 times to about 2.0 times the amount of the ECA, or is approximately equal to the amount of the ECA.

[0267] Q. A method according to any one of the preceding embodiments, wherein the weight ratio of the high-charge fast-inverting cationic fixing polymer and the high-molecular-weight fast-inverting cationic retention polymer added to the papermaking system ranges from

[0268] (i) about 1 / 20 to about 20 / 1 by weight;

[0269] (ii) about 1 / 10 to about 10 / 1 by weight;

[0270] (iii) about 2 / 10 to about 10 / 2 by weight;

[0271] (iv) about 3 / 10 to about 10 / 3 by weight;

[0272] (vi) about 3 / 8 to about 8 / 3 by weight;

[0273] (vii) about 3 / 7 to about 7 / 3 by weight;

[0274] (viii) about 4 / 6 to about 6 / 4 by weight;

[0275] (ix) about 5.5 / 4.5 to about 4.5 / 5.5 by weight; or

[0276] (x) about equal amounts of the fast-inverting cationic retention polymer added to the papermaking system.

[0277] R. A method according to any one of the preceding embodiments, wherein the polymer and the ECA are added to the fibrous raw material containing recycled fibers, optionally to the dilute raw material or the thick raw material, preferably to the thick raw material.

[0278] S. A method according to any one of the preceding embodiments, which includes using hard water and / or recycled fibers.

[0279] T. A method according to any one of the preceding embodiments, wherein the polymer and the ECA are added to the fluid, composition or machine used in the papermaking system.

[0280] U. A method according to any one of the preceding embodiments, wherein

[0281] (i) the fiber suspension contains at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, or even more preferably at least 80% or 100% by weight of kraft fibers or virgin fibers;

[0282] (ii) the polymer and the ECA are added separately to a fiber suspension having a consistency higher than 30 g / l;

[0283] (iii) adding the polymer and the ECA separately to a fiber suspension having a consistency below 20 g / l;

[0284] (iv) adding the polymer and the ECA to the fiber furnish before washing and / or cleaning and / or thickening, wherein the fiber furnish has a consistency of less than about 4%, 2% or 1% (i.e., the dry mass percentage in the furnish);

[0285] (v) adding the polymer and the ECA to the fiber furnish before forming and / or pressing and / or drying, wherein the fiber furnish optionally has a consistency of about 15% to 35% (i.e., the dry mass percentage in the furnish);

[0286] (vi) adding the polymer and the ECA separately to a fiber suspension having a consistency above 20 g / l;

[0287] (vii) the furnish contains starch;

[0288] (viii) the furnish contains at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, or even more preferably at least 80% or 90% by weight of kraft fibers or virgin fibers, and a small amount of recycled fibers, optionally about 10% to about 20% by weight of recycled fibers, and optionally contains a low level of fines;

[0289] (ix) the furnish contains at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, or even more preferably at least 80% or 90% by weight of kraft fibers or virgin fibers, and a small amount of recycled fibers, optionally about 10% to about 20% by weight of recycled fibers, and further optionally contains a high level of fines;

[0290] (x) the furnish contains some fibers obtained from a paper machine that uses only or mainly recycled paper, such as up to 5% to 10% by weight;

[0291] (xi) the furnish contains some fibers derived from recycled paper, old corrugated container board (OCC), mixed office waste (MOW), old magazines (OMG), unbleached kraft pulp, neutral sulfite semi-chemical (NCCS) pulp, and / or mechanical pulp;

[0292] (xii) The raw material contains at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, or even more preferably at least 80% or 90% or 100% of kraft paper fibers or virgin fibers, and optionally contains some recycled fibers obtained from a papermaking process using a paper machine that uses at least 60%, 70%, 80%, 90% or 100% recycled fibers;

[0293] (xiii) The raw material contains some, optionally up to 5% to 10% by weight of OCC recycled fibers, which contain approximately 5% of natural sizing press starch and starch gel that can be recycled for the manufacture of paper or cardboard;

[0294] (xiv) The raw material contains starch optionally derived from recycled fibers and / or broke fibers in the raw material and / or starch is added to the treated fiber raw material;

[0295] (xv) Treatment is carried out before or simultaneously with the addition of other cationic functional polymers or other papermaking chemicals; or

[0296] (xvi) Any combination of the foregoing.

[0297] V. A fiber raw material for pulp, paper or cardboard production, the fiber raw material preferably contains a high content of virgin fibers or kraft paper fibers, such as at least 50% to �0% by weight of virgin fibers or kraft paper fibers, and optionally contains a small amount of recycled fibers, such as up to 5% to 10% by weight of recycled fibers, and / or starch, the fiber raw material contains a composition containing a combination of a cationic polymer and ECA optionally produced according to any one of the foregoing embodiments and / or has been treated with the composition.

[0298] W. The fiber raw material according to embodiment V, which contains at least 50% by weight, preferably at least 60% by weight, more preferably at least 70% by weight, or even more preferably at least 80% or 90% of kraft paper fibers or virgin fibers.

[0299] X. A paper or cardboard produced by the method according to any one of the foregoing embodiments.

[0300] The present invention has been described in detail, and the present invention is further described in the following examples. Although the present invention has been described according to preferred embodiments, it will be apparent to those skilled in the art that changes and substitutions can be applied to the compositions and / or methods described herein without departing from the concepts, spirit and scope of the present disclosure.

[0301] Examples

[0302] Materials and methods used in the examples

[0303] Polymers used in the examples

[0304] The polymers used in the examples, namely the conventional cationic polymers for retention, the high-charge low-Mw cationic polymers (fixing polymers) of the present invention, and the high-molecular-weight fast-reversing polymers (retention polymers), are compared in the following table:

[0305]

[0306] DDA procedure:

[0307] The Dynamic Drainage Analyzer (DDA) was used to evaluate the effect of the polymers on drainage. Additive timing was used to simulate the timing of additives on the machine. The polymers were prepared according to a standard downsizing procedure.

[0308] For each measurement, an aliquot of the furnish was poured into the DDA mixing tank, where the additives were given according to the machine conditions. After mixing, the furnish was drained through a paper machine wire and the filtrate was collected in a container. The drainage time was recorded and used as a measure of drainage performance.

[0309] The turbidity of the filtrate was then measured using a Hach 2100Q turbidimeter. Lower turbidity values indicate better retention of fibers, fines, and colloidal and particulate materials.

[0310] ZDT procedure:

[0311] Z-direction tensile (ZDT) is defined as the maximum tensile stress in the thickness direction that a test strip can withstand before breaking when the test strip is loaded perpendicular to the plane in a tensile instrument. The ZDT test used in the examples follows TAPPI Test Method 541om-10, Internal Bond Strength (Z-direction Tensile) of Paperboard. This test is intended for paperboard and some papers where the internal fiber bond strength (cohesion strength) is lower than the adhesive bond strength of the tape to the sample and / or test platen.

[0312] The following examples are provided for illustrative purposes only and are non-limiting.

[0313] Example 1: Evaluation of the effect of a fast-reversing polymer on drainage time when used as a CCA alternative in an EcoFill Lite system

[0314] This example relates to experiments, the results of which are included in Figure 1 . In these experiments, a target basis weight of 110 g / m 2The NA paper machine for bleached paperboard uses engineered cellulose additives (ECA) to increase the strength of the paper to achieve the ZDT goal. ECA adds additional anionic charge to the furnish, so a retention aid is needed to retain ECA to meet the strength goal. The existing system uses a charge control agent (CCA) to fix ECA to the fibers. In addition to CCA, traditional retention polymers are used to retain fibers, fines, and other papermaking additives.

[0315] [[ID= 3]]In this example, different fast inverse polymers were evaluated as CCA alternatives and as a two-component system, where a higher charge fixative was used to fix ECA to the fibers and a high molecular weight polymer was used as a retention aid. This combination provided the best drainage performance in the DDA test and provided very good retention benefits. The addition time was 10 seconds for ECA, 15 seconds for Polymer A, and 75 seconds for Polymer B.

[0316] The results of these experiments showed that Polymer A, when used as a CCA alternative, performed better than conventional CCA products for drainage, as Figure 1 shown by the results in. Specifically, the drainage results showed that when Polymer A was used to replace CCA and Polymer B was used to replace an exemplary traditional retention aid, the drainage time was improved by 32% to 35%.

[0317] Example 2: Evaluation of the effect of fast inverse polymers on filtrate turbidity when used as CCA alternatives in the EcoFill Lite system

[0318] This example relates to experiments, the results of which are contained in Figure 2 . In these experiments, again, an NA paper machine for bleached paperboard with a target basis weight of 110 g / m 2 [[ID= 18]]was used, which uses engineered cellulose additives (ECA) to increase the strength of the paper to achieve the ZDT goal. As previously discussed, ECA adds additional anionic charge to the furnish, so a retention aid is needed to retain ECA to meet the strength goal. The existing system again uses a charge control agent (CCA) to fix ECA to the fibers. In addition to CCA, traditional retention polymers are used in the existing system to retain fibers, fines, and other papermaking additives.

[0319] In the experiments, the same fast inverse polymers were evaluated as CCA alternatives and as a two-component system by comparing their effect on filtrate turbidity in the DDA system, where a higher charge fixative was used to fix ECA to the fibers and a lower charge polymer was used as a retention aid. The addition time was 10 seconds for ECA, 15 seconds for Polymer A, and 75 seconds for Polymer B.

[0320] The results of these experiments indicate that the combination of Polymer A and Polymer B functions comparably to conventional CCA polymer retention systems, i.e., it provides retention (as measured by turbidity) that is competitive with existing DDA / retention polymer systems.

[0321] Example 3: Machine Tests Comparing the Effects of Polymer A (as a Fixative for ECA) and Polymer B (as a Retention Aid)

[0322] This example relates to experiments, the results of which are contained in Figure 3 . In these experiments, a NA paper machine running bleached, uncolored linerboard was used, and a combination of an amphoteric strength additive and starch was used to achieve strength targets.

[0323] In these experiments, the combination of ECA, Polymer A (used as a fixative for ECA), and Polymer B (used as a retention aid) was shown to provide the highest strength at the lowest dosage, as measured by ZDT. ZDT (Z-directional Tensile) measures the strength in the vertical direction, also known as internal strength. The paper sample was fixed to double-sided tape, and then the prepared sample was fixed to the ZDT measuring head of a tensile testing machine. Then a controlled force was applied to the upper surface of the tape paper sample under timed hold. Then the measuring head was pulled apart under constant stress until the paper sample failed in the Z direction. The force required to break the sample was recorded as the ZDT measurement result and reported in lbf / in2.

[0324] Figure 3 The results in reveal that while existing procedures require 4 kg / T starch and 3 kg / T amphoteric polymer (with CCA added) to meet the performance seen with the Polymer A / Polymer B combination (4 kg / T starch, 1 kg / T ECA, and Polymer A / B combination). In these experiments, Polymer A was added within 10 seconds of adding ECA. As Figure 3 shown, no performance degradation was observed during the machine tests.

[0325] Example 4: Machine tests for evaluating the effects of Polymer A, Polymer B, and ECA

[0326] In this example, experiments were conducted to evaluate the effects of Polymer A and Polymer B when used with an ECA additive under paper machine conditions.

[0327] In these experiments, machine tests were conducted on 61.5# bleached folding carton grade. In addition to starch for retention, the existing system also used ECA and a charge control additive (CCA). During the tests, the effect of the inventive combination (Polymer A / ECA / Polymer B) on machine performance was evaluated. In the experiments, Polymer A was added within 10 to 15 seconds of ECA. The results of these tests reveal that the paper machine was able to make significant improvements to the process.

[0328] Evaluate the mill control process data (parameters taken directly from the machine process data), and compare these results (not shown) with the conventional CCA method. The results show that the combination of the present invention provides at least the following process improvements:

[0329] i) The thick stock flow rate and consistency of the brown stock washer (BSW) sold are reduced by 6%;

[0330] ii) The dye usage is reduced, while at the same time the usage of ground calcium carbonate (GCC) (10 kg / T) and precipitated calcium carbonate (PCC) (20 kg / T) is increased. The normal filler loading is only 10 kg / T PCC;

[0331] iii) Improve the cleaning of the white water circuit; and

[0332] iv) Reduce the drying energy (steam pressure from 462 kPa to 317 kPa)

[0333] Conclusion

[0334] The experiments disclosed in Examples 1 to 4 and Figures 1 to 3 the experimental results shown therein indicate that the combination of the present invention (Polymer A / ECA / Polymer B) provides improved retention of ECA to the fiber web, as demonstrated by improved drainage and filtrate turbidity compared to the conventional (existing) DDA / retention polymer system.

[0335] In addition, the results show that the combination of the present invention (Polymer A / ECA / Polymer B) requires 4.0 kg / T starch and 3.0 kg / T of a conventional amphoteric polymer (CCA added) to meet the performance obtained by the Polymer A / Polymer B combination (4.0 kg / T starch, 1.0 kg / T ECA and Polymer A / B combination) when compared with existing procedures.

[0336] In addition, the results show that the combination of the present invention (Polymer A / ECA / Polymer B) provides improved machine performance when used to promote ECA retention under industrial papermaking conditions.

[0337] The combination of the present invention (Polymer A / ECA / Polymer B) and its method of use have been described in accordance with the preferred embodiments, and the present invention is further defined by the following claims.

Claims

1. A papermaking method, which includes adding an engineered cellulose additive (ECA), optionally to replace virgin fibers and / or starch and / or as a strength enhancer, wherein the papermaking method includes using the following: (i) A high-charge rapid inverse fixed copolymer, which contains 2-(acryloyloxy)ethyl]trimethylammonium chloride (Q9) (cationic) and acrylamide monomers ("fixed polymer"); (ii) An anionic ECA; and (iii) A high molecular weight rapid inverse cationic retention polymer, which contains Q9 (cationic) and acrylamide monomers ("retention polymer"); wherein each is added separately to the papermaking system.

2. A method for treating fibrous raw materials and / or process water used in pulp, paper, or paperboard production, the fibrous raw materials and / or process water preferably mainly containing kraft fibers or virgin fibers, the method including obtaining the fibrous raw materials and / or process water, and treating the fibrous raw materials and / or process water with the following: (i) A high-charge rapid inverse fixed copolymer, which contains Q9 (cationic) and acrylamide monomers ("fixed polymer"); (ii) An anionic ECA; and (iii) A high molecular weight rapid inverse cationic retention polymer, which contains Q9 (cationic) and acrylamide monomers ("retention polymer"); wherein each is added separately to the fibrous raw materials and / or process water.

3. A method for manufacturing paper or paperboard, wherein a fibrous web is formed from an aqueous suspension of fibers, the method including: - Providing an aqueous fiber suspension, which preferably mainly contains kraft fibers or virgin fibers, and optionally further contains recycled fiber materials and / or coated broke, - Optionally diluting the aqueous fiber suspension, - Delivering the aqueous fiber suspension to a headbox, draining the aqueous fiber suspension on a wire screen to form a wet fibrous web, and - Pressing and drying the wet fibrous web to obtain a web of paper or paperboard, the method including separately adding (i) a high-charge rapid inverse fixed copolymer containing Q9 (cationic) and acrylamide monomers, (ii) ECA, and (iii) a high molecular weight rapid inverse cationic retention polymer containing Q9 (cationic) and acrylamide monomers, wherein each of (i), (ii), and (iii) is added separately during manufacturing.

4. The method according to claim 1, 2, or 3, wherein the high-charge rapid inverse fixed copolymer (fixed polymer) promotes the fixation of the ECA and optionally other colloidal particles to anionic fibers, and / or the high molecular weight rapid inverse cationic polymer (retention polymer) promotes the retention of the ECA and optionally fines and other colloidal particles in the fibrous web.

5. The method according to any one of the preceding claims, wherein (i) the high charge rapid inverse fixing polymer comprises 30 mol% to 40 mol% of Q9 monomer and has a standard viscosity (SV) between 1.7 cps and 2.0 cps; and / or, the high molecular weight rapid inverse cationic retention copolymer comprises 20 mol% to 30 mol% of Q9 monomer and has a standard viscosity (SV) between 3.0 cPs and 3.5 cPs.

6. The method according to any one of the preceding claims, wherein (i) the high charge rapid inverse fixing polymer is first added to the papermaking system; (ii) after adding the high charge rapid inverse fixing polymer, ECA is added to the papermaking system; and (iii) after adding ECA to the papermaking system, the high molecular weight rapid inverse cationic retention polymer is added.

7. The method according to any one of the preceding claims, wherein the combined dosage of the retention polymer and the fixing polymer is equal to or greater than ECA.

8. The method according to any one of the preceding claims, wherein the dosage range of the retention polymer is 0.1 kg to 5 kg per ton; and / or the dosage range of the fixing polymer is 0.1 kg to 5 kg per ton.

9. The method according to any one of the preceding claims, wherein the combined dosage range of the fixing polymer and the retention polymer is 0.2 kg to 5 kg per ton.

10. The method according to any one of the preceding claims, wherein the dosage range of the ECA is 0.2 kg to 5 kg per ton.

11. The method according to any one of the preceding claims, wherein (i) the intervals between steps (i) and (ii) and (iii) are sufficient to achieve adequate mixing, and according to the shear dynamics during mixing, the intervals are typically at least 3 seconds to 5 minutes.

12. The method according to any one of the preceding claims, which comprises one or more other additives commonly used in papermaking, such as dyes, starches, microbicides, other fixing agents or retention agents, sizing agents, etc.

13. The method according to any one of the preceding claims, wherein (i) the high charge rapid inverse fixing polymer enhances the fixing of ECA to the anionic fibers without disrupting the formation of the paper, optionally at high polymer dosage levels; (ii) the high charge rapid inverse fixing polymer promotes the fixing of anionic ECA products and other anionic colloidal particles to the anionic fibers; (iii) the high charge rapid inverse fixing polymer promotes the fixing of ECA more effectively than traditional charge fixing / control agents (CCA) such as CC610 (polyacrylamide-DADMAC dispersion), polyamines, and polyDADMAC solution polymers; (iv) the high molecular weight rapid inverse cationic retention polymer interacts more effectively with colloids and fines than linear and conventional high Mw cationic polymers (typical SV range = 4.5 cPs to 5.5 cPs). (v) The high molecular weight fast reverse cationic retention polymer enhances the total retention of the ECA, fines, and fibers on the paper machine; (vi) The combination of the high charge fast reverse cationic fixing polymer and the high molecular weight fast reverse cationic retention polymer causes a synergistic effect on the drainage of the paper machine; (vii) The combination of the high charge fast reverse cationic fixing polymer and the high molecular weight fast reverse cationic retention polymer causes a synergistic effect on the total first pass retention of the engineered cellulose additive (ECA) on the ECA enhanced paper grade; (viii) The combination of the high charge fast reverse cationic fixing polymer and the high molecular weight fast reverse cationic retention polymer promotes dye retention; (ix) The combination of the high charge fast reverse cationic fixing polymer and the high molecular weight fast reverse cationic retention polymer reduces the amount of dye required; (x) The combination of the high charge fast reverse cationic fixing polymer and the high molecular weight fast reverse cationic retention polymer reduces the amount of filler required; (xi) The combination of the high charge fast reverse cationic fixing polymer and the high molecular weight fast reverse cationic retention polymer improves dryer efficiency; (xii) The combination of the high charge fast reverse cationic fixing polymer and the high molecular weight fast reverse cationic retention polymer promotes the retention of dyes and / or fillers; (xiii) The combination of the high charge fast reverse cationic fixing polymer and the high molecular weight fast reverse cationic retention polymer reduces the amount of starch required; (xiv) The combination of the high charge fast reverse cationic fixing polymer and the high molecular weight fast reverse cationic retention polymer has a synergistic effect on the retention of ECA, fines, and fibers on the produced paper; or (xv) Any combination of the foregoing.

14. The method according to any one of the preceding claims, wherein the total dose by weight of the high charge fast reverse cationic fixing polymer and the high molecular weight fast reverse cationic retention polymer ranges from about 0.8 times to about 20 times the amount of the ECA added to the papermaking system, about 1.0 times to about 10 times the amount of the ECA, about 1.0 times to about 5.0 times the amount of the ECA, about 1.0 times to about 3.0 times the amount of the ECA, about 1.0 times to about 2.0 times the amount of the ECA, or approximately equal to the amount of the ECA.

15. The method according to any one of the preceding claims, wherein the dose ratio by weight of the high charge fast reverse cationic fixing polymer and the high molecular weight fast reverse cationic retention polymer added to the papermaking system ranges from (i) about 1 / 20 to about 20 / 1 by weight; (ii) about 1 / 10 to about 10 / 1 by weight; (iii) about 2 / 10 to about 10 / 2 by weight; (iv) about 3 / 10 to about 10 / 3 by weight; (vi) about 3 / 8 to about 8 / 3 by weight; (vii) about 3 / 7 to about 7 / 3 by weight; (viii) about 4 / 6 to about 6 / 4 by weight; (ix) from about 5.5 / 4.5 to about 4.5 / 5.5 by weight; or (x) about equal amounts by weight of the fast-inverting cationic retention polymer added to the papermaking system.

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