Abstract: Low amidine content poly(N-vinylformamide-co-vinylamine) (PVAm), is described, as well as processes of making and providing same in fresh or aged formats, and the usage of such polymer to increase papermaking retention and drainage rate and enhance paper dry strength, and other applications.

Abstract: A composition includes at least one hydrophilic polymer containing primary (—NH2) and/or secondary (—NHR) amine groups and at least one saccharide containing a reducible function. A method of increasing the strength of paper includes the step of contacting the paper with a composition comprising (i) at least one hydrophilic polymer containing at least two groups which are independently the same or different a primary amine group or a secondary amine group and at least one saccharide containing a reducible function. A hydrogel composition is formed from a mixture of at least one hydrophilic polymer containing at least two groups which are independently the same or different a primary amine group or a secondary amine group and at least one saccharide containing a reducible function.

Abstract: The invention concerns a glossy or scintillating paper provided with a roughness more than 30 ml/mm measured in accordance with the ISO 8791-2 standard, entirely manufactured on a paper machine, and characterized in that it comprises reflecting microplates or microbeads of dimensions less than 300? incorporating at least one optically transparent material in their structure.

Abstract: Polymeric bonding agents having a “triggerable” bonding functionality and which are in the form of particles or fibers, are blended with papermaking fibers prior to formation of a tissue web. After the web is dewatered, and advantageously during or after drying, the triggerable bonding functionality is activated to strengthen the resulting sheet structure. Tissue sheets prepared in this manner can exhibit an improved combination of softness, bulk and strength.

Abstract: The invention concerns an improved method for making paper, which uses a branched polymer prepared in invert emulsion as the main retention agent, and bentonite as a secondary retention agent (dual type system). The two additions are separated by a step for shearing the fibrous suspension (or mass). The invention results in highly improved retention and also highly improved dewatering. Moreover, it enables the bentonite content in white water to be reduced.

Abstract: A thermosetting resin comprising a reacted A) first partially crosslinked glyoxalated polymer comprising a reacted (i) first polyacrylamide backbone and (ii) a first glyoxal component; and B) a second crosslinked glyoxalated polymer comprising a reacted (i) second polyacrylamide backbone and (ii) a second glyoxyal component; such that the first polyacrylamide backbone has a molecular weight that is less than the molecular weight of the second polyacrylamide backbone; and the first polyacrylamide backbone and the second polyacrylamide backbone have a weight ratio ranging from 75:25 to 95:5. Methods for making and using the resin. Fibrous substrates made with the resin.

Abstract: A method for producing paper, cardboard or similar materials, comprising, separately or in a mixture, adding to a fibrous suspension: at least one main retention agent comprising a cationic (co)polymer, and at least one dual retention agent comprising a crosslinked cationic (co)polymer obtained in the form of a dispersion and placed in solution prior to its introduction into the fibrous suspension with gentle stirring. The crosslinked cationic (co)polymer having—a UL viscosity of between 1.3 and 2.7 cps, preferably between 1.5 and 2.4 cps, and—an apparent cationicity ratio of between 25 and 75%. Optionally, before or after the dual agent or the main retention agent are added, one or more tertiary retention agent(s) selected from the group comprising mineral particles and organic polymers carrying anionic charges, is added to the suspension.

Abstract: Process for finishing paper and paper products by treating the surface of paper or paper products with at least one finishing agent, at least one finishing agent being applied in the form of a pattern on the top and/or bottom of paper or paper products, and the papers and paper products obtainable by the process.

Abstract: The invention improves a sizing effect even on paper containing no internal sizing agent and improves productivity by making solution polymerization in a small amount of an organic solvent. The invention provides a cationic surface sizing agent composed of a copolymer obtained by solution polymerization of (a) 15 to 35% by weight of a tertiary amino group-containing monomer, (b) 30 to 85% by weight of C1 to C4 alkyl (meth)acrylate, and (c) 1 to 50% by weight of styrenes in an organic solvent in the presence of a chain transfer agent. The copolymer may be subjected to cationization treatment with a quaternization agent. As a constituent monomer of the copolymer, 0 to 20% by weight of another copolymerizable vinyl monomer (d) may be contained. The cationic surface sizing agent is applied to paper.

Abstract: A process for producing paper, board and cardboard in the presence of an aqueous slurry of components comprising finely divided fillers coated at least partly with water-soluble amphoteric copolymers, which involves adding, further to the aqueous slurry of components comprising finely divided fillers, at least one cationic and/or amphoteric polymer comprising as structural element no esters of unsaturated carboxylic acids with quaternized amino alcohols to the fiber suspension prior to sheet forming.

Abstract: Cellulosic substrates are treated with compound(s) containing at least two primary amino groups and compounds containing at least one ?-ketocarbonyl group. The substrates exhibit good strength and hand properties.

Abstract: A method of modifying the surface of a substrate which comprises a fibrous material. According to the present invention, the surface is brought into contact with a type of amphiphilic block copolymer which comprises one or several hydrophilic polymeric blocks and one or several hydrophobic polymeric blocks. Approximately 0.01-3 g/m2 of the amphiphilic block copolymer are applied onto the surface. With the help of the present invention, it is possible to effectively modify the surface of paper in such a manner that it produces a good surface for printing, for instance for ink-jet printing.

Abstract: The invention relates to a tissue product comprising (a) tissue fibrous web incorporated throughout the tissue product; (b) a temporary wet strength agent capable of forming hemi-acetal bonds with the fibers of the web to prevent immediate degradation of the web when the tissue product contacts water; and (c) a composition containing a degrading agent selected from the group consisting of alkaline agents, oxidizing agents, nucleophilic agents, and combinations thereof; such that the tissue product has at least one surface and the degrading agent is located substantially throughout the surface of the fibrous web in an amount sufficient to make the fibrous web exhibit (i) an immediate wet tensile strength of at least 90% of the wet strength as compared to a web that does not contain a degrading agent and (ii) a wet soak decay that is at least a ten point improvement as compared to a tissue fibrous web that does not contain a degrading agent.

Abstract: A method for making storage-stable glyoxalated inter-copolymers with higher and adjustable charge density suitable for use as a strengthening agent for paper. The glyoxalated inter-copolymers can be used to enhance the strength of paper, particularly recycled paper and mechanical printing paper.

Abstract: A composition comprising a polymer that is a reaction product of: a copolymer backbone comprising; (i) at least one acrylamide component, (ii) at least one co-monomer, (iii) at least one initiator and (iv) at least one chain transfer agent; and at least one cellulose reactive agent; wherein the copolymer backbone and cellulose reactive agent are combined with water to form a solution wherein the concentration of the copolymer backbone is about 0.1 to about 19% by weight based on the total weight of the solution. A process to make high solids copolymer backbone with low molecular weight and narrow molecular weight distribution has also been developed by a continuous polymerization process under refluxing conditions. In this process, a mixture of the acrylamide, co-monomer and chain transfer agent and the initiator are simultaneously and continuously added to a heel of water.

Abstract: Fabric-creped absorbent sheet has an MD bending length of about 3.5 cm or more as well as an absorbency of about 3 g/g or more. The sheet is preferably produced without through drying or dry creping and is a low-dust product especially suitable for automatic towel dispensers.

Abstract: A solution with a salt-sensitive polymer binder for use in fibrous webs, where the binder contains a copolymer comprising repeat units derived from butyl acrylate, methyl methacrylate and amino functionalized alkyl acrylate or methacrylate or amino functionalized alkyl acrylamide or methacrylamide optionally including monomers such as vinyl acetate and/or vinyl acetate/ethylene. The binder solution is prepared by emulsion-polymerizing a copolymer and then neutralizing the copolymer with acid to make it water soluble. The binders are particularly suitable for strengthening nonwoven fibrous webs in disposable articles such as wet-wipes, personal care products, diapers, and the like and retain their salt-sensitivity with or without divalent metal scavengers.

Abstract: A method of improving retention and drainage in a papermaking process is disclosed. The addition of an associative polymer, a poly(vinylamine) and optionally a siliceous material to the papermaking slurry to improve retention and drainage is disclosed. Additionally a method to improve retention and drainage comprising addition of an organic microparticle, a poly(vinylamine) and optionally a siliceous material to the papermaking slurry is disclosed. A composition comprising an associative polymer, and a poly(vinylamine) and optionally further comprising cellulose fiber is disclosed.

Abstract: A water-soluble interjacent complex that includes a first water-soluble polymer and one or more water-soluble monomers polymerized to form a second water-soluble polymer in the presence of the first water-soluble polymer. The water-soluble interjacent complex forms a solution in water that is free of insoluble polymer particles. The interjacent complexes may be used to treat a waste sludge by adding an effective amount thereof to the waste sludge. The interjacent complexes may also be used in making paper by adding an effective amount thereof to a pulp or a forming sheet at a suitable location on a paper making machine. The interjacent complexes may further be used as a rheology modifier in aqueous systems by adding an effective amount thereof to an aqueous medium to effect a desired viscosity, rheology, or flow curve property.

Abstract: Compositions and methods of producing paper-based materials are disclosed. In general, the techniques utilize an amine-containing polymer, such as chitosan, to functionalize one or more components of a mixture used to form materials such as paper-based materials. Such components can include the fibers of a pulp and/or filler particles. In one instance, either the pulp or the filler particles are functionalized, but not both. Such functionalization can improve the qualifies of a paper-based material relative to when such functionalization is not utilized. Techniques and compositions are also described to further improve the qualities of a paper material by utilizing a complementary polymer which can couple with the amine-containing polymer.

Abstract: Compositions and methods of producing paper-based materials are disclosed. The techniques can utilize an amine-containing polymer, such as chitosan, to functionalize one or more components of a mixture used to form materials such as paper-based materials. Such components can include the fibers of a pulp and/or filler particles. Techniques and compositions are also described to further improve the qualities of a paper material by utilizing a complementary polymer which can couple with the amine-containing polymer. Other compositions and methods are directed to forming paper-based materials that are expandable.

Abstract: Print media and methods of making print media are disclosed. One exemplary print medium, among others, includes a substrate having a fibrous component. In addition, a cationic guanidine polymer compound or salt thereof and a metallic salt are each disposed within the fibrous component of the substrate.

Abstract: Provide a paper offering good paper strength properties in terms of strength and stiffness, high smoothness and excellent printing quality by adjusting the ash content in paper to a range of 3 to 40 percent by solid weight and allowing the paper to contain a pre-coagulated filler having an average particle size of 10 to 80 ?m as measured by the laser diffraction method, wherein such filler is obtained by processing a filler using a composite acrylamide copolymer comprising (A) an anionic polysaccharide and (B) a cationic and/or amphoteric acrylamide copolymer.

Abstract: The invention provides a paper quality improver for papermaking that allows improvement in the bulky value and the optical properties such as brightness and opacity as well as in the paper strength of a sheet obtained by papermaking a pulp material. The paper quality improver for papermaking is a paper quality improver for papermaking containing a copolymer (A) having a constituent unit derived from at least one nonionic monomer having a solubility parameter of 20.5 (MPa)1/2 or less and a constituent unit derived from at least one anionic or cationic monomer and a surfactant (B) at a certain ratio, the quality improver providing at least one paper quality improving effect of: (i) standard improved bulky value: 0.02 g/cm or more; (ii) standard improved opacity: 1.0 point or more; and (iii) standard improved brightness: 0.5 point or more.

Abstract: The invention relates to a process for producing paper, board and cardboard of high dry strength by separately adding a polymer comprising vinylamine units and a polymeric anionic compound to a paper pulp, dewatering the pulp and drying the paper products, which comprises using as polymeric anionic compound at least one copolymer obtainable by copolymerizing (a) at least one N-vinylcarboxamide of the formula in which R1 and R2 are H or C1- to C6 alkyl, (b) at least one monoethylenically unsaturated monomer comprising acid groups, and/or the alkali metal, alkaline earth metal or ammonium salts thereof, and if appropriate (c) other monoethylenically unsaturated monomers, and if appropriate (d) compounds having at least two ethylenically unsaturated double bonds in their molecule.

Abstract: Finely divided, starch-containing polymer dispersions obtainable by emulsion copolymerization, with redox initiators, of ethylenically unsaturated monomers from the group consisting of (a) from 45 to 55% by weight of at least one optionally substituted styrene, methyl methacrylate, acrylonitrile and/or methacrylonitrile, (b) from 15 to 29% by weight of at least one C1-C12-alkyl acrylate and/or one C2-C12-alkyl methacrylate and (c) from 0 to 10% by weight of at least one other ethylenically unsaturated copolymerizable monomer in an aqueous medium in the presence of (d) from 15 to 35% by weight of a degraded cationized starch which has a molar mass Mw of from 1000 to 65 000, the sum (a)+(b)+(c)+(d) being 100% and being based on the total solids content, processes for the preparation of such polymer dispersions by emulsion polymerization of the monomers (a), (b) and (c) in an aqueous medium with redox initiators in the presence of (d) cationic starch, and use of the starch-containing polymer dispersions as size

Abstract: The invention provides a method and apparatus for optimally feeding an ASA emulsion into a papermaking process. An intense transmission of ultrasonic energy rapidly and efficiently forms an ASA emulsion. Nearly simultaneous to forming the emulsion, the emulsion is fed into a high-speed dual conduit feeding apparatus, which quickly mixes the ASA emulsion with other chemicals and feeds the mixture directly into a papermaking process. The invention operates so fast that virtually no hydrolysis of the ASA occurs. This both prevents damage to the papermaking machinery and improves the quality of the produced paper. The invention operates 10-20 times faster than mechanical based emulsion methods and requires 1/7 as much energy to operate. The invention also self-monitors the process and can automatically correct any detected problems with the fed ASA emulsion.

Abstract: Hydrophobically modified polymers containing vinylamine or ethylenimine units and obtainable by reacting (a) polymers containing vinylamine or ethylenimine units with (b) compounds of the formula R-A-(EO, PO, BuO)n—X??(I), where R is C4- to C26-alkyl or C4- to C26-alkenyl, A is O, NH or COO, EO is an ethylene oxide unit, PO is a propylene oxide unit, BuO is a butylene oxide unit, n is from 1 to 250 and X is a functional group which can be covalently bonded to an OH group, process for the preparation of hydrophobically modified polymers containing vinylamine or ethylenimine units by reacting polymers containing vinylamine or ethylenimine units with a water repellent of the formula I and use of the polymers thus obtainable as an additive to paperstock in papermaking.

Abstract: The present invention is directed to compositions comprising a cellulose reactive functionalized polyvinylamine first adduct, compositions comprising combinations of the cellulose reactive functionalized polyvinylamine first adduct and cellulose reactive functionalized polyvinylamide second adduct, methods for preparing first adduct and second adduct blends and finally methods of increasing the wet or dry strength of paper by incorporation into the paper furnish or coating a paper or board with said adducts.

Abstract: A process of making paper by providing a cellulosic suspension comprising cellulosic fibres and optionally fillers, dewatering the cellulosic suspension on a wire or mesh to form a sheet and drying the sheet in which a polymeric additive is included in the process, in which the polymeric additive is a polymer comprising an ethylenically unsaturated water-soluble or potentially water-soluble monomer and an ethylenically unsaturated monomer carrying a reactive group.

Abstract: The invention relates to a composition comprising a (a) a temporary wet strength agent component capable of forming hemi-acetal bonds with the fibers of a tissue web to provide initial wet strength, subsequent rapid degradation of the initial wet strength when the tissue web contacts water; and (b) a sizing agent component capable of imparting water-repelling properties to the tissue web; such that the strength agent component and the sizing agent component are present in sufficient amounts so that when the composition is added to a tissue pulp slurry during a tissue-making process, tissue made from the tissue-making process exhibits a combination of (1) improved initial wet tensile, (ii) improved decay, and (iii) absorbency.

Abstract: The instant invention relates to certain cross-linked polyamides and their use in the paper and board industry for improving dry strength. The polyamide from the reaction of a di- or tri-primary amine with a di- or tri- or tetra carboxylic acid is further reacted with a di- or tri-functional cross-linking compound to give a cationic or anionic product with no reactive groups.

Abstract: A composition comprising a functionalized water-soluble, cationic, thermosetting, cellulose reactive polymer with a doubly structured backbone that is the reaction product of: (a) a copolymerized (i) acrylamide component, (ii) cationic co-monomer component and (iii) at least one multifunctional crosslinking monomer component; and (b) a cellulose reactive agent component; such that the acrylamide component, the cationic co-monomer component, the multifunctional crosslinking monomer component, and the cellulose reactive agent component are in an amount sufficient amount to produce a polymer that imparts strength to a fibrous substrate when the polymer is added to paper stock during a papermaking process. The invention also relates to methods for making and using such a composition.

Abstract: The present invention relates to a creping aid composition comprising a film-forming semi-crystalline polymer and a vehicle system comprising a cationic polymer resin, a water soluble anionic film forming polymer, and water, wherein the net Mutek charge of the vehicle system is less than about ?200 ?eq/g solid and the pH of the creping aid composition is greater than the pH of the vehicle system.

Abstract: A process for the manufacture of paper, board or similar products, comprises first of all, adding, to the paper pulp fibrous suspension, at least one main retention aid composed of a cationic (co)polymer. Then optionally the flocs obtained are sheared. Subsequently there is added to the suspension, separately or as a mixture, in any order: at least one secondary retention aid chosen from the group consisting of silica derivatives and anionic or amphoteric organic polymers, and at least one tertiary retention aid composed of a crosslinked anionic organic polymer with a size of greater than or equal to 1 micrometer and exhibiting an intrinsic viscosity of less than 3 dl/g.

Abstract: A composition includes water; at least one hydrophilic polymer containing at least two groups which are independently the same or different a primary amine group or a secondary amine group and at least one saccharide containing a reducible function as described above. The hydrophilic polymer and the saccharide are mixed to form a reaction mixture and reacted to increase the viscosity of the reaction mixture. The reaction is then substantially terminated by reducing the pH of the composition.

Abstract: The invention related to process for the production of paper from an aqueous suspension containing cellulosic fibers, and optional fillers, which comprises adding to the suspension (i) a cationic vinyl addition polymer prepared by polymerizing one or more ethylenically unsaturated monomers comprising a cationic monomer; (ii) an anionic polymer having one or more aromatic groups selected from the group consisting of polymers obtained by condensation of formaldehyde with benzene-based and naphthalene-based compounds, polyurethanes, polysaccharides, and lignin-based polymers; wherein (i) and (ii) are separately added to the suspension; and (iii) a low molecular weight cationic organic polymer having a molecular weight in the range of from 2,000 to about 700,000; or an anionic microparticulate material; and forming and draining the obtained suspension on a wire.

Abstract: There is provided a filled paper containing a coated filler obtained by coating a filler with a acrylamide copolymer (composite PAM) comprising (A) an anionic polysaccharide and (B) a cationic and/or an amphoteric acrylamide copolymer. The composite PAM is obtained, for example, by mixing the component (A) and the component (B). Since the filler is treated with a combination of the components (A) and (B) different from each other in charge properties and structure, suitable coagulation effect can be attained and the coated filler has excellent affinity for pulp slurry. Therefore, even in the case of a highly filled paper, a large paper strengthening effect can be attained by using a small amount of the chemical agent.

Abstract: The present invention provides a wet-spun non-woven fabric composed of inorganic fibers containing bundled inorganic fibers and a binder component for binding the fibers, wherein the average number of the fibers in each bundle is 1.5 to 20 and the average Z/X value represented by the following formula in the cross section of the non-woven fabric is 0.9 or below: (number of adjacent fibers in the thickness direction in each bundle)/(number of adjacent fibers in the plane direction in each bundle)=Z/X, and a method for producing a wet-spun non-woven fabric, which comprises the steps of dispersing inorganic fibers in an aqueous medium in the presence of an anionic dispersion stabilizer, adding a cationic compound to the obtained fiber dispersion to bundle the fibers and thereby preparing a fiber dispersion containing the resultant fiber bundles, making a sheet from the obtained fiber dispersion containing the fiber bundles by wet method and applying a binder to the obtained sheet.

Abstract: A method of preparing a modified diallyl-N,N-disubstituted ammonium halide polymer and use of the polymer in combination with one or more high molecular weight, water soluble cationic, anionic, nonionic, zwitterionic or amphoteric polymers for increasing retention and drainage in a papermaking furnish.

Abstract: This invention relates to a process for preparing sized paper and paperboard which incorporates in the paper and paperboard at the size press size a composition comprising one or more “hydrophobic polymers” wherein hydrophobic polymers, the amount of such polymers and the weight ratio of starch to such polymer in the composition are selected such that the paper and paper board exhibits a Cobb Value equal to or less than about 25 and to a sized paper or paperboard web formed by the process.

Abstract: The present invention relates to flat paper products having an increased relative wet strength and softness, a method for the production of the same and also the use of paper products of this type in the form of tissue products. This is achieved by a cross-linkage of the cellulose fibres contained in the paper product with a cationic graft copolymer which is constructed on the basis of polyethyleneoxide- or polyethyleneglycol segments and polyethyleneimine segments.

Abstract: The present disclosure includes a regenerated cotton board material comprised of dry cut cotton lint fiber, and wood fiber. The regenerated cotton board material may further include non-cellulosic fibers such as synthetic fibers or other natural fibers. In an alternate embodiment, a cotton board material may be manufactured from a mixture of dry cut cotton lint fiber and a binder material. A method for forming a regenerated cotton board material according to the present disclosure includes forming an aqueous slurry fiber furnish from a combination of dry cut cotton lint fiber, and wood fiber. The fiber furnish is then wet processed, calendared to remove the bulk of the water, and dried.

Abstract: ASA sizing emulsions are described, as well as emulsifying agents containing starch and a terpolymer of acrylamide/quaternary ammonium compound/glyoxal, and an ASA blend that contains ASA and a co-surfactant blend of anionic surfactant and nonionic surfactant. Processes for sizing paper products with the emulsions are also described.

Abstract: A composition includes water; at least one hydrophilic polymer containing at least two groups which are independently the same or different a primary amine group or a secondary amine group and at least one saccharide containing a reducible function as described above. The hydrophilic polymer and the saccharide are mixed to form a reaction mixture and reacted to increase the viscosity of the reaction mixture. The reaction is then substantially terminated by reducing the pH of the composition.

Abstract: Disclosed is a method for manufacture and application of a polymeric papermaking additive, which can be used in paper manufacture as an agent for improving retention, drainage, product strength and paper machine operation. The additive according to this disclosure is a polymer of epichlorohydrin and contains primary amino groups. Under neutral or acidic conditions these primary amino groups become cationic, which assures good adsorption of the polymer onto anionic fibers and fines of pulps used for production of paper or paperboard. By adsorbing on several fibers or fines, the polymer can increase the retention of fines and fillers. Primary amino groups of this polymer can also form chemical bonds with carbonyl groups of cellulose, lignin and hemicellulose, which are especially abundant in the fibers and fines of mechanical pulps. The cross-linking of fibers and fines by chemical bonds can increase the initial strength of wet web and the strength of rewetted paper.

Abstract: The present invention relates to methods for manufacturing paper or paperboard with improved strength, the methods comprising the addition of the reaction product of a cationic polyacrylamide and an aqueous aldehyde generating compound or a glyoxal releasing compound, or glyoxal itself, prepared at the mill site at high concentrations, then diluted and added into a fiber furnish prior to forming or drying of the paper or paperboard sheet.

Abstract: Process for the production of paper, board and cardboard by draining a paper stock with sheet formation in the presence of a retention aid system comprising (i) at least one polymer comprising vinylamine units, in the form of the free bases, of the salts and/or in quaternized form, as the sole cationic polymer, (ii) at least one linear, anionic polymer having a molar mass Mw of at least 1 million and/or at least one branched, anionic, water-soluble polymer and/or bentonite and/or silica gel and (iii) at least one particulate, anionic, crosslinked, organic polymer having a mean particle diameter of at least 1 ?m and an intrinsic viscosity of less than 3 dl/g, and use of the retention aid system comprising the components (i), (ii) and (iii) as an additive in the production of paper, board and cardboard.

Abstract: In a method of producing a sheet of paper and/or cardboard and similar products, prior to the formation of the sheet from a fibrous suspension, at least two dry strength agents are added to the suspension either separately in any order or mixed together and at one or more injection points, namely: a first agent corresponding to a product for Hofmann degradation in solution on a base (co)polymer comprising at least one non-ionic monomer which is selected from the group containing acrylamide and/or methacrylamide, N,N dimethylacrlamide and/or acrylonitrile; and a second agent corresponding to a (co)polymer having an anionic charge density greater than 0.1 meq/g. The Hofmann degradation product comprises an organic polymer produced at a concentration greater than 3.5% by weight, and preferably greater than 4.5% and the first and second agents are each introduced into the pulp suspension at a concentration of between 0.

Abstract: A method for making a sheet of paper and/or cardboard and the like, comprises, prior to forming said sheet, adding to the fibrous suspension, separately or mixed, in any sequence of introduction, into one or more injection points, at least three dry strength agents respectively: first agent corresponding to a (co)polymer having a cationic filler density higher than 1 meq/g and exhibiting primary amine functions; a second agent corresponding to a synthetic organic (co)polymer having cationic filler density higher than 0.1 meq/g; and a third agent corresponding to a (co)polymer having an anionic filler density higher than 0.1 meq/g.