ES2625625T3 - Procedure to enhance the dry strength of the paper by treatment with polymers containing vinylamine and polymers containing acrylamide - Google Patents

Procedure to enhance the dry strength of the paper by treatment with polymers containing vinylamine and polymers containing acrylamide Download PDF

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ES2625625T3
ES2625625T3 ES10799243.0T ES10799243T ES2625625T3 ES 2625625 T3 ES2625625 T3 ES 2625625T3 ES 10799243 T ES10799243 T ES 10799243T ES 2625625 T3 ES2625625 T3 ES 2625625T3
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polymer
containing
acrylamide
daltons
propyl
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Clement L. Brungardt
Jonathan M. Mckay
Richard J. Riehle
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Solenis Technologies Cayman LP
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Solenis Technologies Cayman LP
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Priority to PCT/US2010/061750 priority patent/WO2011090672A1/en
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    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H21/00Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/14Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
    • D21H21/18Reinforcing agents
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20Macromolecular organic compounds
    • D21H17/33Synthetic macromolecular compounds
    • D21H17/34Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/35Polyalkenes, e.g. polystyrene
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20Macromolecular organic compounds
    • D21H17/33Synthetic macromolecular compounds
    • D21H17/34Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/37Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20Macromolecular organic compounds
    • D21H17/33Synthetic macromolecular compounds
    • D21H17/34Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/37Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
    • D21H17/375Poly(meth)acrylamide
    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20Macromolecular organic compounds
    • D21H17/33Synthetic macromolecular compounds
    • D21H17/46Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H17/54Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen
    • D21H17/56Polyamines; Polyimines; Polyester-imides

Abstract

Process for the production of paper, cardboard and cardboard with improved dry strength comprising adding to the wet end of a papermaking machine (a) a polymer in aqueous solution containing vinylamine having a molecular weight of from 75,000 daltons up to 750,000 daltons and (b) an amphoteric aqueous solution polymer containing acrylamide having a molecular weight from 75,000 daltons to 1,500,000 daltons, in which the sum of the anionic and cationic monomers incorporated into the acrylamide-containing polymer comprise from 5% to 50% on a molar basis of all monomers incorporated into the acrylamide-containing polymer, in which the polymer in aqueous solution is a polymer that forms a completely homogeneous solution in water when diluted to 1% on a base of dry solids.

Description

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DESCRIPTION

Procedure to enhance the dry strength of the paper by treatment with poffmeros containing vinyl amine and poffmeros containing acrylamide

Field of the Invention

This invention relates to the improvement of the dry strength of the paper using a method of treating a pulp slurry with a combination of a vimmer containing vinylamine and an amphoteric poffmero containing acrylamide.

Background of the invention

The papermaking industry is constantly looking for new synthetic additives to improve the dry strength of paper products. An improved dry strength can provide a higher yield product, but it can also allow the paper manufacturer to use less cellulosic fiber to achieve a particular performance objective. In addition, the increased use of recycled fiber results in a weaker sheet, forcing the paper manufacturer to increase the base weight of the sheet or to use synthetic additives that provide strength. The options that are known have various economic and technical limitations. For example, according to U.S. Patent No. 6,939,443, the use of combinations of polyamide-epichlorohydrin (PAE) resins with anionic polyacrylamide additives with specific charge densities and molecular weights can enhance the dry strength of a product of paper. However, these combinations can also raise the wet strength of the resulting paper to the point that reprocessing the waste paper is extremely difficult and inefficient.

It is widely known that acrylamide poffmeros or copoffmeros incorporating acrylamide and a monomer such as diallyldimethylammonium chloride, when treated with a dialdetffdo compound such as glyoxal, result in resins that can also significantly enhance the dry strength of the paper, although they have very limited permanent wet strength properties, allowing the paper manufacturer to easily reprocess waste paper. However, these resins also have their limitations. These additives have a very short shelf life due to viscosity instability or are shipped with a very low active solids content. In addition, when added in larger quantities, the performance of such acrylamide-containing dialdetffdo-modified acrylamide tends to reach a yield, producing a high-yield product difficult to manufacture.

Polyvinylamine resins have become popular in the papermaking industry not only because they give a sheet an increase in dry strength, but also due to its easy handling and application, as well as increased retention and drainage. They provide the papermaking machine. However, when added in increasing amounts, they have the negative effect of over-flocculating the sheet due to the heavy cationic charge that these resins carry. Over-flocculation results in a weaker and poorly formed finished product.

Other inventions have tried to increase the positive effects of polyvinylamine. According to U.S. Patent No. 6,824,650 and European Patent No. 1,579,071, the combination of polyvinylamine with glyoxalated polyacrylamide resins in a slurry paste results in a product with higher dry strength. However, the aforementioned drawbacks of glyoxalated polyacrylamides, particularly solids with low active component content of the product and limited product viscosity stability, are clearly at stake.

U.S. Patent No. 6,132,558 discloses a papermaking system in which a pulp slurry is first treated with a highly cationic poffmero, including vinylamine-containing poffers, of molar mass of 5000 to 3,000,000 daltons and subsequently with a second cationic poffmero containing molar mass acrylamide of more than 4,000,000 daltons, subjected to a shear stage, to subsequently be treated with a finely divided inorganic flocculation agent, such as bentonite, colloidal silica or clay.

US Patent Publication 2008/0000601 discloses a papermaking process in which the pulp slurry is treated with a poffmero, including vinylamine containing poffmeros, with a molar mass of more than 1,000,000 daltons, as well as with a second poffmero, including cationic poffmeros containing acrylamide, with a molar mass of more than 2,500,000 daltons, all in the absence of finely divided inorganic flocculating agents.

U.S. Patent No. 6,746,542 discloses a papermaking method in which a pulp slurry is treated with starch that has been modified at a temperature above the gelatinization temperature of the starch with a highly cationic poffmero, including poffmeros containing vinylamine, with a molar mass of less than 1 000 000 daltons. The pulp slurry is subsequently treated with a second poffmero, including cationic poffmeros containing acrylamide, with a molar mass of more than 1 000 000 daltons.

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US Patent Publication 2008/0196852 discloses a retention aid system for the manufacture of paper comprising at least one polymer, including polymers containing vinylamine, at least one linear anionic polymer with a molar mass of more than 1,000,000 daltons and at least one organic, crosslinked, anionic and particulate polymer.

The combination of polymers containing vinylamine with polymers containing acrylamide may be the simplest and most effective means of producing a high-performance paper product, while maintaining the productivity of the papermaking machine and reprocessing paper. scrap However, examples of the prior art that may include these polymers have significant drawbacks. For example, the previous examples may require special dosing apparatus, additional steps to treat the starch before adding it to the pulp slurry or polymers of high molar mass which can result in an over flocculation of the slurry when added in quantities. enough to affect dry strength.

Brief Description of the Invention

Treatment of a pulp slurry with an aqueous solution polymer containing vinyl amine in combination with amphoteric aqueous solution polymers containing acrylamide results in a paper with improved dry strength.

This combination provides the greatest efficiency when the content of active polymer solids of the acrylamide-containing aqueous solution polymer ranges from 5% to 50% by weight and the content of the sum of the cationic and anionic monomers in the polymer it contains. Acrylamide ranges from 5% to 50% on a molar basis of the total monomeric content and the molecular weight of the acrylamide-containing polymer ranges between 75,000 Daltons and 1,500,000 Daltons.

The vinylamine-containing polymer provides the greatest efficacy when it contains at least 50% on a molar base of W-vinylformamide monomer, at least 10% of it has been hydrolyzed in the final product and has a molecular weight ranging from 75 000 daltons and 750 000 daltons. The aqueous solution containing the vinylamine-containing polymer has a total polymer solids content from 5% to 30% by weight.

The invention is a process for the production of paper, cardboard and cardboard with improved dry strength which comprises adding to the wet end of a papermaking machine a (a) an aqueous solution polymer containing vinylamine having a molecular weight from 75,000 daltons up to 750,000 daltons and (b) an amphoteric aqueous solution polymer containing acrylamide having a molecular weight from 75,000 daltons to 1,500,000 daltons, in which the sum of the anionic and cationic monomers incorporated into the polymer containing Acrylamide comprises from 5% to 50% on a molar basis of all monomers incorporated into the acrylamide-containing polymer, in which the polymer in aqueous solution is a polymer that forms a completely homogeneous solution in water when diluted to 1 % on a dry solids basis.

In one embodiment of the process, the vinylamine-containing polymer has a W-vinylformamide content of at least 50% on a molar basis of the total charged monomer, at least 10% thereof has been hydrolyzed into the final polymer and a content of active polymer from 5% to 30% on a weight basis.

In one embodiment of the process, the acrylamide-containing aqueous solution polymer contains a total cationic and / or amphoteric monomeric filler from 5% to 50% on a molar basis and has an active polymer content from 5% to 50 % on a weight basis.

In one embodiment of the process, the acrylamide-containing aqueous solution polymer is from an aqueous dispersion polymer.

In one embodiment of the process, the acrylamide-containing aqueous solution polymer contains a cationic monomeric charge from 5% to 50% on a molar basis, has an active polymer content from 5% to 50% on a base of weight and comprises at least one cationic monomer selected from the group consisting of diallyldimethylammonium chloride (DADMAC), 2- (dimethylamino) ethyl acrylate, 2- (dimethylamino) ethyl methacrylate, 2- (diethylamino) ethyl acrylate, methacrylate 2- (diethylamino) ethyl, 3- (dimethylamino) propyl acrylate, 3- (dimethylamino) propyl methacrylate, 3- (diethylamino) propyl acrylate, 3- (diethylamino) propyl methacrylate, W- [3- (dimethylamino ) propyl] acrylamide, W- [3- (dimethylamino) propyl] methacrylamide, W- [3- (diethylamino) propyl] acrylamide, W- [3-

 (diethylamino) propyl] methacrylamide,
 [2- (acryloyloxy) ethyl] trimethylammonium chloride, [2-

 (methacryloxy) ethyl] trimethylammonium,
 [3- (acryloyloxy) propyl] trimethylammonium chloride, [3-

 (methacryloxy) propyl] trimethylammonium, (methacrylamidopropyl) trimethylammonium.
 3- (acrylamidopropyl) trimethylammonium chloride and 3- chloride

In one embodiment of the process, the amphoteric aqueous solution containing acrylamide is composed of a polyelectrolytic complex consisting of a polymer in aqueous solution containing acrylamide and a cofactor carrying an opposite charge.

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In one embodiment of the process, the vinylamine-containing polymer and the acrylamide-containing polymer are a mixture of individual products and the cationic part of the acrylamide-containing amphoteric polymer is generated from at least one monomer selected from the group consisting of chloride of diallyldimethylammonium (DADMAC), N- [3- (dimethylamino) propyl] acrylamide, N- [3- (dimethylamino) propyl] methacrylamide, N- [3- (diethylamino) propyl] acrylamide, N- [3-

(diethylamino) propyl] methacrylamide, 3- (acrylamidopropyl) trimethylammonium chloride and 3- (methacrylamidopropyl) trimethylammonium chloride.

In one embodiment of the process, the vinylamine-containing polymer and acrylamide-containing polymer are added to the wet end of a papermaking machine in a relationship between the vinylamine-containing polymer and the acrylamide-containing polymer from 10: 1 to 1 : 50 to a total of 1.25% on a weight basis of dry paper pulp, based on the active polymer solids of the polymer products.

Detailed description of the invention

As used herein, the singular terms "one / one" and "the" are synonymous and are used interchangeably with "one / one or more" or "at least one / one" unless that the context clearly indicates what the opposite means. Accordingly, for example, the reference to "a compound" herein or in the appended claims may refer to a single compound or more than one compound.

As used herein and unless otherwise indicated, it is understood that the terms "polymers containing vinylamine" mean homopolymers of vinylamine (eg, polyvinyl amine or fully hydrolyzed polyvinylformamide), copolymers of vinylamine with other comonomers, partially hydrolyzed polyvinylformamide, partially hydrolyzed vinylformamide copolymers, vinylamine terpolymers, homo- and vinylamine copolymers manufactured by Hofmann modification of acrylamide polymers or vinylamine-containing polymers that are chemically modified after the polymerization described. in U.S. Patent Publication Number 2009/0043051 or Number 2008/0196851.

As used herein and unless otherwise indicated, the term "acrylamide-containing polymer" refers to the amphoteric aqueous solution-containing polymer containing acrylamide.

As used herein and unless otherwise indicated, the term "polymer in aqueous solution" refers to a polymer that forms a completely homogeneous solution in water when diluted to 1% on a solid basis. dry, in the absence of any cosolvent. For example, a polymer in aqueous solution does not include oil-in-water or water-in-oil emulsions. Examples of polymers in aqueous solution may include polymers in aqueous dispersion, as described in U.S. Patent 5,541,252 and 7,323,510, as well as in U.S. Patent Publications No. 2002/198317 and No. 2008/0033094.

The invention is based on the discovery that the performance of a papermaking machine and the paper products thus obtained can be greatly improved by treating the pulp slurry with a vinyl-containing polymer in combination with a polymer that It contains acrylamide with a particular molecular weight and charge attributes, as described below. The use of a polymer containing vinylamine only provides resistance and drainage performance in the papermaking system; however, when added in increasing quantities, the yield of the paper product reaches a limit first and then deteriorates, due in large part to the overflow of the paper web in formation. It has been unexpectedly found that the addition of vinylamine-containing polymer together with the addition of acrylamide-containing polymers in aqueous solution that have a substantial amphoteric charge results in a product with resistance performance that goes beyond that which can be achieved using polymers. containing vinylamine or containing acrylamide alone; furthermore, the excellent drainage performance achieved using a polymer containing vinylamine can be substantially maintained using said combination of polymers.

The vinylamine-containing polymer provides the greatest efficiency when its molecular weight is from 75,000 daltons to 750,000 daltons, more preferably from 100,000 daltons to 600,000 daltons, most preferably from 150,000 daltons to 500,000 daltons. The molecular weight can be from 150,000 daltons to 400,000 daltons. Below the molecular weight threshold of 75,000 daltons, little or no resistance performance is observed and no substantial improvement in drainage performance is observed. The polymer containing vinylamine is not cooked with the starch before adding it to the slurry. A polymer containing vinylamine with a molecular weight above 750,000 daltons, in general, will adversely affect the formation in the dosages required for an improvement of dry strength due to the tendency to over-flocculate the leaf, resulting in a lower resistance. A polymer in aqueous solution that contains vinylamine of more than 750,000 daltons or is normally produced with such high viscosities that the handling of the product is extremely difficult or alternatively is produced with a product polymer solids content so low that it causes It is not profitable to store and ship the product.

The percentage of active polymer solids of the vinylamine-containing polymer ranges from 5% to 30%, more preferably between 8% and 20% by weight of the total content of vinylamine-containing polymer product. By

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Below 5% of active polymer solids, polymers in higher molecular weight aqueous solution may be possible, but the product becomes ineffective when shipping and transportation costs are taken into account. On the other hand, as the active polymer solids increase, the molecular weight of the polymer should decrease globally so that the aqueous solution remains easily pumpable. Therefore, a practical relationship can be established between the total polymer solids of the vinylamine-containing polymer product and the molecular weight of said polymer and a correlation can be established between these parameters and the polymer yield.

The yield of the polymer containing vinylamine depends on the amount of primary amine present in the product. The vinylamine moiety is normally generated by acidic or basic hydrolysis of W-vinyl acrylamide groups, such as W-vinylformamide, W-vinyl acetamide or W-vinylpropionamide, most preferably W-vinylformamide. The polymer containing vinylamine provides the greatest efficiency in improving the dry strength of a paper product and / or the drainage performance of a papermaking system when the amount of W-vinylformamide is at least 50% on a molar base of the hydrolyzed polymer. After hydrolysis, at least 10% of the W-vinylformamide originally incorporated in the resulting polymer should be hydrolyzed. Unintentionally limited to a theone, the hydrolyzed W-vinylformamide group may exist in various structures in the final polymer product, such as primary or substituted amine, amidine, guanidine or amide structures, in open or cyclic chain forms after the hydrolysis.

The acrylamide-containing polymer provides the greatest efficacy when it contains a substantial amount of positively charged comonomer (s). Without wishing to limit itself to a teona, the positively charged monomer allows the acrylamide-containing polymer to adhere to cellulose fibers due to a charge-loading interaction with negatively charged substances in the pulp slurry, including, but not limited to: fibers of pulp, hemicellulose, oxidized starch normally found in recycled cellulose, anionic strength adjuvants such as carboxymethyl cellulose and anionic wastes. The incorporation of cationic groups to the acrylamide-containing polymer, in general, is not detrimental to the drainage performance of the papermaking system. Unintentionally limited to a theone, the hydrogen bonding components of the acrylamide-containing polymer, such as amide groups, are effective in improving the dry strength of the paper product.

Suitable comonomers used to confer cationic charge to the polymer include, but are not limited to, diallyldimethylammonium chloride (DADMAC), 2- (dimethylamino) ethyl acrylate, 2- (dimethylamino) ethyl methacrylate, 2- (diethylamino) acrylate ethyl, 2- (diethylamino) ethyl methacrylate, 3- (dimethylamino) propyl acrylate, 3- (dimethylamino) propyl methacrylate, 3- (diethylamino) propyl acrylate, 3- (diethylamino) propyl methacrylate, W- [ 3- (dimethylamino) propyl] acrylamide, W- [3- (dimethylamino) propyl] methacrylamide, W- [3- (diethylamino) propyl] acrylamide, W- [3-

(dimethylamino) propyl] methacrylamide, [2- (acryloyloxy) ethyl] trimethylammonium chloride, [2- (methacryloxy) ethyl] trimethylammonium chloride, [3- (acryloyloxy) propyl] trimethylammonium chloride, [3- (methacryloxy) chloride ) propyl] trimethylammonium, 3- (acrylamidopropyl) trimethylammonium chloride and 3- (methacrylamidopropyl) trimethylammonium chloride. Such cationic monomers can affect the performance of the amphoteric polymer when incorporated into the main structure of the polymer.

In the amphoteric polymer, the amount of the cationic monomer plus the amount of an anionic monomer described below can be from 5% to 50%, more preferably from 15% to 40%, on a molar basis of all monomers incorporated into the polymer containing acrylamide. The acrylamide-containing polymer can be crosslinked with an agent such as methylene bisacrylamide (MBA), provided that the molecular weight and charge guidelines are met, as described herein.

The incorporation of an anionic comonomer to the acrylamide-containing polymer together with the cationic comonomer, forming an amphoteric polymer containing acrylamide, is also effective in improving the dry strength of a paper product produced in that way. Without wishing to limit itself to a theone, the anionic comonomer allows the amphoteric polymer to form a coacervate complex with a wide variety of substances found in a recycled paste slurry, including, but not limited to: a polymer containing vinylamine, a flocculant or coagulant charged cationically, cationic or amphoteric starch, wet strength adjuvants of polyamidoamine-epichlorohydrin or other amphoteric polymer containing acrylamide. In addition, the combination of cationic and anionic monomers in the acrylamide-containing polymer improves or does not adversely affect the drainage performance of a papermaking system compared to an acrylamide-containing polymer that only uses an anionic comonomer. Suitable anionic comonomers include, but are not limited to, acrylic acid, methacrylic acid, itaconic acid, itaconic anhydride, maleic anhydride, maleic acid, styrene sulfonate, vinyl sulfonate, 2-acrylamido-2-methylpropane sulfonate (AMPS) . Alternatively, such substructures can be generated by hydrolysis of a precursor structure (for example, generation of methacrylic acid in the main structure of the polymer by hydrolysis of methyl methacrylate after formal polymerization). The amount of charged monomer incorporated into the acrylamide-containing polymer may affect the polymer's performance. Such anionic monomers can be used in an amphoteric polymer containing acrylamide and the amount of the anionic monomer plus the amount of a cationic monomer described below can be from 5% to 50% on a molar basis of all monomers incorporated into the polymer that Contains acrylamide The acrylamide-containing polymer can be crosslinked with an agent such as methylene bisacrylamide (MBA), provided that the molecular weight and charge guidelines are met, as described herein.

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The properties of an amphoteric polymer in aqueous solution containing acrylamide as defined above can also be effectively produced by the use of a polyelectrolytic complex containing acrylamide. When combined with a pyrimer containing vinylamine, said acrylamide-containing polyelectrolytic complex can also produce similar benefits to those described above when combining vinylamine-containing poftmeros with cationic or amphoteric poftmeres containing acrylamide. Although polyelectrolytic complexes have been disclosed in various ways, such as in European Patent Publication No. 1,918,455 A1, the unexpected result of efficacy of such polyelectrolytic complexes in dry resistance generation is disclosed herein, which It goes beyond what the polyelectrolytic complex can provide by itself and that can be achieved when used in combination with poftmeros containing vinylamine. An acrylamide-containing polyelectrolytic complex contains a poftimer containing cationic, amphoteric or anionic charge acrylamide, as well as a second complementary charge polymer. For example, an anionic polymer containing acrylamide produced by polymerization of acrylamide with one of the suitable anionic monomers listed above may form a polyelectrolytic complex with a cationic polymer, which may or may not include acrylamide. Such cationic poftmeros include, but are not limited to, alkylamine-epichlorohydrin poftmeros, acrylamide-containing cationic poftmeros as described above, polyamidoamine-epichlorohydrin poftmeros and polyethyleneimine poftmeres. The acrylamide-containing polyelectrolytic complex may also comprise a cationic acrylamide-containing polymer and an anionic polymer. Such anionic poftmeros include, but are not limited to, poftmeros and copoftmeros of (meth) acrylic acid, poftmeros and copoftmeros of maleic acid and carboxymethylcellulose. The polyelectrolytic complex containing acrylamide can be added to the slurry for the manufacture of paper as an individual combined product or as two independent products, most preferably as an individual combined product. The amphoteric polyelectrolytic complex carries a net charge, expressed in milliequivalents per gram (meq / g) of active poftimer content. The amphoteric polyelectrolytic complex, in general, has the highest stability and utility in combination with vinylamine-containing poftmeros when the net charge is in the range from -2 meq / g to +2 meq / g, more preferably from -1 meq / g up to +1 meq / g. The particle size is also an important parameter of the amphoteric polyelectrolytic complex. The complex has the greatest utility when the particle size ranges between 0.1 microns and 50 microns, more preferably between 0.2 and 5 microns. Other guidelines for active poftmer solids, the preferred methods for adding the acrylamide-containing poftimer to the pulp slurry and the relationship between the pyrimer containing vinylamine and the acrylamide-containing poftimer apply to the total formulation of the acrylamide-containing polyelectrolytic complex , not only to the part of the pyrimer containing acrylamide of the complex.

The aqueous solution polymer containing acrylamide, whether it is characteristically an amphoteric poftmero or an amphoteric polyelectrolytic complex as defined above, more effectively improves the dry strength of a paper product when its molecular weight is greater of 75,000 daltons. A molecular weight of less than 75,000 daltons is not easily conserved in the sheet and, above all, does not confer significant dry strength properties on the paper, although it could be manufactured in such a way that it would have a poftmer solids content above 50 % on a weight basis. However, a polymer containing acrylamide of more than 1,500,000 daltons, and especially more than 2,500,000 daltons, can show significant disadvantages. Although, at lower dosages, such high molar mass poftmeros can provide good drainage performance, achieving high dry strength usually requires higher dosages of poftmeros. A poftmero of this type can significantly over-flocculate the sheet when added to a dosage that could have a significant impact on dry strength, thereby resulting in poor formation and / or poor dry strength. In one embodiment, the molecular weights of the cationic or amphoteric poftmeros in aqueous solution containing acrylamide may be in the range from 75,000 to less than 1,500,000 daltons or may be from 100,000 to less than 1 250,000 daltons or may be from 100,000 to less than 1,000,000 daltons. In addition, a polymer of this molecular weight, in general, is synthesized by emulsion polymerization or inverse emulsion, thereby adding significant environmental and safety risks, inconveniences and risks. For example, in the formulation of a reverse emulsion product, petroleum or other hydrocarbon is required, such as mineral oil, which adds a significant cost to the product even if it does not add value to the product; Significant additional preparation equipment used to store, stir, dilute and invert emulsions is required; additional chemicals are needed to break or reverse the emulsion; and the emulsion or reverse emulsion type poftmeros also contain significant amounts of volatile organic compounds, generating a significant danger to health and / or safety. In theone, a product can be achieved in an aqueous solution containing acrylamide of molecular weight of more than 1,500,000 daltons; however, a product of this type will probably have less than 5% of solid solids, making a product of this type less useful, cost-effective and convenient for a paper manufacturer or comprising such a high viscosity that the handling of the product signals extremely difficult Therefore, in general, there is a practical relationship between total poftmer solids and molecular weight and a general correlation between these parameters and poftmero performance can be established.

In one embodiment, the acrylamide-containing poftimer is an aqueous dispersion poftimer. Acrylamide-containing poftmeros produced by amphoteric aqueous dispersion polymerization are of particular practical importance when combined with vinylamine-containing poftmeros. Specific examples are described in U.S. Patent No. 7,323,510, as well as in U.S. Patent Publication No. 2008/0033094. These water-soluble poftmeros can have molecular weights from 300,000 daltons to 1,500,000 daltons or from 400,000 daltons to less than 1 250,000 daltons, while maintaining a solids content of poftmero

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from 10% to 50% on a weight basis. These polymers have a molecular weight that is somewhat smaller than that of traditional flocculants and, therefore, are less effective than polymers containing higher molecular weight acrylamide as retention and drainage polymers at low dosage levels, although they can generate Excellent drainage performance when used at adequate dosage levels to improve dry strength without over-flocking a cellulose sheet in formation. Without wishing to limit itself to a theona, the interaction of polymers containing vinyl amine with polymers containing acrylamide in aqueous dispersion or with other components of a papermaking system, including but not limited to oxidized starch, hemicellulose or anionic wastes, can create networks of particularly extensive hydrogen bonds, providing additional dry strength to a paper product without thereby having substantial negative effects on the drainage performance of the papermaking system.

The vinylamine-containing polymer and the acrylamide-containing polymer can be combined with each other in a mixture of individual product. The ratios between the vinylamine-containing polymer and the acrylamide-containing polymer range from 10: 1 to 1:50, more preferably in the range from 5: 1 to 1:10, more preferably in the range from 3: 1 to 1: 5, most preferably in the range from 2: 1 to 1: 4.

The total amounts of the mixture of polymers that can be added to the pulp slurry at the wet end of the papermaking machine range from 0.05% to 1.25% of the weight of dry paper pulp on a base. of total polymer solids. Mixtures can be produced with polymers containing vinylamine and cationic or amphoteric polymers containing acrylamide, but most preferably with cationic polymers containing acrylamide. Unintentionally limited to a theone, the anionic components of amphoteric polymers containing acrylamide can ionically interact with the cationic components of polymers containing vinylamine, particularly primary amine groups, to form gels and high viscosity products that are not useful for paper manufacturing Unintentionally limited to a theone, polymers containing cationic monomers with ester groups, for example, [2- (acryloxy) ethyl] trimethylammonium chloride, can react in aqueous solutions with primary amine groups of the vinylamine-containing polymer to form amide groups or they can be hydrolyzed to generate the above-mentioned anionic moieties, any of which can form a gelled product or a product of prohibitively high viscosity that is not useful in papermaking. In addition, the hydrolysis of the relatively expensive cationic acrylate group represents a significant economic loss when considering the cationic polymer containing acrylamide. Unintentionally limited to a theone, cationic monomers containing amide, such as 3- (acrylamidopropyl) trimethylammonium chloride or diallyldimethylammonium chloride (DADMAC) are resistant both to hydrolysis in aqueous solutions and to reaction with primary amine groups, which makes them preferred as cationic monomers in the acrylamide-containing polymer to be mixed with the vinylamine-containing polymer.

Polymers containing vinylamine and polymers containing acrylamide can be added during the papermaking process at the wet end either in the thick pulp or in the thick pulp; either before or after a shear point. The acrylamide-containing polymer may first be added to the wet end of the papermaking machine, followed by the polymer containing vinylamine; the acrylamide-containing polymer can be added separately at the same point on the wet end of the papermaking machine as the vinylamine-containing polymer; the acrylamide-containing polymer can be added at the same point on the wet end of a papermaking machine as a mixture of individual product; or, more preferably, the vinylamine-containing polymer may be added first at the wet end of the papermaking machine, followed by the acrylamide-containing polymer. The polymer containing vinylamine is not reacted with the starch before being added to the slurry.

The vinylamine-containing polymer and the acrylamide-containing polymer can be added to the wet end of a papermaking machine in a ratio of 1:50 to 10: 1 between the vinylamine-containing polymer and the acrylamide-containing polymer as a ratio of polymer solids; more preferably in a ratio from 1:10 to 5: 1, more preferably in the range from 1: 5 to 3: 1, most preferably in the range from 1: 5 to 2: 1. The total amounts of the mixture of polymers that can be added to the pulp slurry at the wet end of the papermaking machine range from 0.05% to 1.25% of the weight of dry paper pulp on a solid basis. of total polymer.

In another embodiment, this invention can be applied to any of the various qualities of paper that benefit from improved dry strength, including but not limited to lining cardboard, bag, paperboard, copy paper, carton, roll paper , file folder, newsprint, cardboard for boxes, cardboard for packaging, printing and writing, of silk, for wipes and publication. These qualities of paper can be composed of any typical paper pulp fiber including wood pulp, bleached or unbleached kraft, sulfate, semi-mechanical, mechanical, semi-chemical and recycled. They may or may not include inorganic fillers.

The embodiments of the invention are defined in the following examples. It should be understood that these examples are provided by way of illustration only. Therefore, various modifications of the present invention, in addition to those shown and described herein, will be apparent to those skilled in the art from the above description. Although the invention has been described with reference to particular means, materials and embodiments, it should be understood that the invention is not limited to the particular cases disclosed and that it extends to all

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equivalents within the scope of the appended claims.

Examples

Polyvinylamine is abbreviated as PVAm. Exclusion chromatography per size (SEC) was used to measure molecular weight. The analysis was carried out using gel permeation columns (CATSEC 4000 + 1000 + 300 + 10o) and Waters 515 series chromatographic equipment with a mixture of 1% NaNO3 / 0.1% trifluoroacetic acid in H2O: CH3CN 50:50 as a mobile phase. The flow rate was 1.0 ml / min. The detector was a Hewlett Packard 1047A differential refractometer. The column temperature was set at 40 ° C and the detector temperature was 35 ° C. The average molecular weight in number (Mn) and average in weight (Mw) of the polymers with respect to the commercially available standard low molecular weight poly (2- vinylpyridine) were calculated.

Net charges or net charge densities (Mutek) of the ionized polymers of the present invention were measured at pH 7.0 using a colloid titration method. The charge density (meq / g) is the amount of net charge per unit weight, in milliequivalents per gram of active polymer. The polymer sample is titrated with a titrant of opposite charge. For net cationic polymers, the titrant used is potassium polyvinyl sulfate (PVSK) and for net anionic polymers the titrant used is poly (dimethyldiallylammonium chloride) (DADMAC). The titrant is added until a potential of 0 mV is achieved using an automatic titrator (Brinkmann Titrino) at a fixed titration rate (0.1 ml / dose, 5 seconds) and a Mutek particle charge detector (model PCD 03 , BTG, Mutek Analytic Inc., 2141 Kingston Ct., Marietta, Ga, USA) which means the detection of the endpoint.

Lining cardboard was manufactured using a papermaking machine. The pulp was 100% recycled paper with a hardness of 50 ppm, an alkalinity of 25 ppm, 2.5% GPC D15F oxidized starch (Grain Processing Corp., Muscatine, IA) and a conductivity of 2000 uS / cm. The pH of the system was 7.0, unless indicated otherwise, and the refining of the paper pulp was approximately 380 CSF with the temperature of the pulp at 52 ° C. The basis weight was 0.1625 kgf per square meter Unless otherwise indicated, Stalok 300 cationic starch (Tate & Lyle PLC, London, UK) and PerForm® PC 8713 flocculant (Hercules Incorporated, Wilmington, DE) were added ) to the wet end of the papermaking machine in an amount of 0.5% and 0.0125% of dry paper pulp, respectively. Polymers containing vinylamine and containing acrylamide were added as described in the previous examples as dry strength agents to the wet end of the papermaking machine at the indicated levels, expressed as a percentage of the weight of active polymer component in front of the dry paper pulp. In general, it is accepted that the dosages normally used for dry strength polymers in the pilot papermaking machine are much larger (i.e. at least double) than those that can be used in a commercial papermaking machine. Ring crush, dry Mullen burst and dry tensile tests were used to measure the effects of dry strength. All dry strength results are expressed as a percentage of the dry strength of paper made without a dry strength resin.

The drainage efficiency of the various polymer systems was compared using one of the two tests. One test is the refining test according to Canadian standards (Canadian Standard Freeness Test, CSF). The dose of the active polymer component varies as indicated in the tables. The results are summarized in the following tables and the drainage yields of these compositions are expressed as an increase in percentage with respect to the blank.

Another method for evaluating the performance of the drainage procedure is the vacuum drainage test (vacuum drainage test, VDT). The configuration of the device is similar to that of the Buchner funnel assay as described in various reference books on filtration, for example, see Perry's Chemical Engineers' Handbook, 7th edition (McGraw-Hill, New York, 1999), pags. 18-78. The VDT consists of a 300 ml magnetic Gelman filter funnel, a 250 ml specimen, a quick disconnect, a water trap and a vacuum pump with a vacuum regulator and indicator. The VDT test was carried out by first adjusting the vacuum to 254 mm Hg and placing the funnel properly on the specimen. Then, 250 g of 0.5% by weight paper pulp were loaded into a beaker and then the required additives were added according to the treatment program (eg, starch, vinylamine-containing polymer, acrylamide-containing polymer, flocculants) to the stirring paste provided by a rod stirrer. The paste was then poured into the filter funnel and the vacuum pump was started while, simultaneously, a timer was started. The drainage efficiency is reported as the time required to obtain 230 ml of filtrate. The results of the two drainage tests were normalized and expressed as a percentage of the drainage performance observed against a system that did not include polymers containing vinylamine and containing acrylamide.

Polymer A is a vinylamine-containing polymer such as Hercobond® 6363 (available from Hercules Incorporated, Wilmington, DE) with a molecular weight in the range of 100,000 daltons to 500,000 daltons with an active polymer solids content of 9% at 15%, a load of W-vinylformamide from 75% to 100% and a range of hydrolysis from 50% to 100%.

Polymer B is a vinylamine-containing polymer such as Hercobond® 6350 (available from Hercules Incorporated, Wilmington, DE) with a molecular weight in the range of 100,000 daltons to 500,000 daltons with a content of

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active polymer solids from 9% to 15%, a W-vinylformamide load from 75% to 100% and a hydrolysis range from 30% to 75%.

Polymer C is an amphoteric polymer containing acrylamide such as Hercobond® 1205 (available from Hercules Incorporated, Wilmington, DE) with a molecular weight in the range of 100,000 daltons to 500,000 daltons with a content of active polymer solids of 10 % to 25% and a total monomeric charge of anionic and cationic monomers from 8% to 20% of the total monomeric charge.

Reference Polymer D is an acrylamide-containing cationic polymer such as Hercobond® 1200 (available from Hercules Incorporated, Wilmington, DE) with a molecular weight in the range of 100,000 daltons to 500,000 daltons, a content of active polymer solids from 10% to 25% and a monomeric cationic charge of 20% to 40%.

Comparative Polymer E is an anionic polymer containing acrylamide such as Hercobond® 2000 (available from Hercules Incorporated, Wilmington, DE) with an anionic monomeric charge in the range of 5% to 20%.

Reference Polymer F and Reference Polymer G are acrylamide-containing aqueous dispersion cationic polymers such as Praestaret® K325 and K350, respectively (available from Ashland Inc., Covington, KY) with a molecular weight in the range of 500,000 Daltons at 1,500,000 Daltons, an active polymer solids content of 20% to 45% and a cationic monomeric charge of 10% to 40%.

Polymer H is an amphoteric polyelectrolytic complex containing acrylamide such as Hercobond® 1822 (available from Hercules Incorporated, Wilmington, DE) with a molecular weight in the range of 100,000 daltons to 500,000 daltons with an active polymer solids content of 10% to 25% and a net charge from -2 meq / g to +2 meq / g.

Reference Polymer K is an acrylamide-containing cationic polymer such as Praestamin® CL (available from Ashland Inc., Covington, KY) with a molecular weight in the range of 100,000 Daltons to 400,000 Daltons with a polymer solids content assets from 15% to 30%. The cationic comonomer of the reference polymer K is 3- (acrylamidopropyl) trimethylammonium chloride. The reference polymer K may be combined with polymers containing vinylamine such as polymer A and polymer B to form an individual product.

EXAMPLE 1

Table 1 shows the results of a test on a pilot papermaking machine using Polymer A, Amphoteric Polymer C and reference cationic Polymer D. The pH of the system was adjusted to 6.5. Alum (Croydon, PA) and HipHase 35 rosin glue (Hercules, Inc., Wilmington, DE) were used in an amount of 0.5% and 0.3% of the dry paper pulp, respectively. OptiPlus 1030 amphoteric starch (National Starch, Bridgewater, NJ) was added instead of Stalok 300 cationic starch, also in 0.5% of dry paper pulp.

Table 1. Strength and drainage properties of paper made of Polymer A and a polymer containing acrylamide.

 Entry
 Additive 1% Additive 2% Dry traction Mullen er dry burst Ring crush Drainage

 one
 - - - - 100 100 100 100

 2
 Polymer A 0.050 - - 102.4 106.2 105.7 110

 3
 Polymer A 0.125 - - 103.2 110.2 108.7 131

 4
 - - Polymer C 0.100 104.5 105.7 104.8 107

 5
 - - Polymer C 0.250 103.8 113.0 110.1 110

 6
 Polymer A 0.050 Polymer C 0.100 102.8 108.0 110.4 121

 7
 Polymer A 0.125 Polymer C 0.100 112.8 116.8 112.6 142

 8
 Polymer A 0.088 Polymer C 0.175 106.5 112.7 117.8 137

 9
 Polymer A 0.050 Polymer C 0.250 110.4 109.2 114.2 121

 10
 Polymer A 0.125 Polymer C 0.250 108.9 121.0 116.9 153

 eleven
 - - Polymer D * 0.100 103.2 93.1 104.6 129

 12
 - - Polymer D * 0.250 106.5 106.2 109.9 150

 13
 Polymer A 0.050 Polymer D * 0.100 103.2 98.2 107.0 137

 14
 Polymer A 0.125 Polymer D * 0.100 105.1 108.3 111.4 137

 fifteen
 Polymer A 0.088 Polymer D * 0.175 107.7 113.0 110.9 150

 16
 Polymer A 0.050 Polymer D * 0.250 104.6 107.7 109.5 142

 17
 Polymer A 0.125 Polymer D * 0.250 106.8 117.4 107.2 147

* Reference polymer

Table 1 shows that the resistance could be significantly improved by the addition of the acrylamide-containing polymer and that the drainage performance was maintained, if not improved, by adding more of the polymer than

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Contains acrylamide It is noted that the dosages normally used for dry strength polymers in the pilot papermaking machine are much larger (i.e. at least twice) than comparable dosages from an efficiency point of view in a machine manufacturing commercial paper For example, if 0.10% of additive is an effective amount for a dry strength polymer in the pilot papermaking machine, then the effective amount in the commercial machine will be approximately 0.05% or less.

EXAMPLE 2

Table 2 shows the drainage performance of three different acrylamide-containing polymer additives using the same white water and paper pulp as indicated in the strength tests illustrated in Table 1. The drainage performance was evaluated using the CSF test. as indicated above. Entries 18 to 23 are shown for comparison.

Table 2 Drainage properties of paper pulp made using various polymers containing acrylamide with Polymer A.

 Entry
 Additive 1% dry paper pulp Additive 2% dry paper pulp% drain

 one
 - - - - 100

 2
 Polymer A 0.050 - - 110

 3
 Polymer A 0.125 - - 131

 4
 - - Polymer C 0,100 107

 5
 - - Polymer C 0.250 110

 6
 Polymer A 0.050 Polymer C 0.100 121

 7
 Polymer A 0.125 Polymer C 0.100 142

 8
 Polymer A 0.088 Polymer C 0.175 137

 9
 Polymer A 0.050 Polymer C 0.250 121

 10
 Polymer A 0.125 Polymer C 0.250 153

 eleven
 - - Polymer D * 0.100 129

 12
 - - Polymer D * 0.250 150

 13
 Polymer A 0.050 Polymer D * 0.100 137

 14
 Polymer A 0.125 Polymer D * 0.100 137

 fifteen
 Polymer A 0.088 Polymer D * 0.175 150

 16
 Polymer A 0.050 Polymer D * 0.250 142

 17
 Polymer A 0.125 Polymer D * 0.250 147

 18
 - - Comparative polymer E 0,100 96

 19
 - - Comparative polymer E 0.250 94

 twenty
 Polymer A 0.050 Comparative polymer E 0.100 110

 twenty-one
 Polymer A 0.125 Comparative polymer E 0.100 134

 22
 Polymer A 0.088 Comparative polymer E 0.175 118

 2. 3
 Polymer A 0.050 Comparative polymer E 0.250 104

 24
 Polymer A 0.125 Comparative polymer E 0.250 134

* Reference polymer

Table 2 demonstrates that the drainage performance of the pulp slurry is weaker when the anionic polymer containing acrylamide (Comparative Polymer E) is used compared to the amphoteric and cationic polymers containing acrylamide (Polymer C and Reference Polymer D ). It is noted that the dosages normally used for dry strength polymers in the pilot papermaking machine are much larger (i.e. at least double) than comparable dosages from an efficiency point of view in a machine manufacturing commercial paper For example, if 0.10% of additive is an effective amount for a dry strength polymer in the pilot papermaking machine, then the effective amount in the commercial machine will be approximately 0.05% or less.

REFERENCE EXAMPLE 3

Table 3 shows the results of a test on a pilot papermaking machine using a polymer containing vinylamine and a cationic polymer containing acrylamide. In this example, as in all the following examples, the pH was maintained at 7.0, alum was not included in the raw materials and no sizing agents were employed.

Table 3. Results of a test in machine of manufacture of pilot paper at pH 7.0 and in the presence of Polymer B and the reference cationic Polymer D containing acrylamide.

Entry | Additive 1 | % | Additive 2 | % | Traction in | Pop Mullen in | Crush on | Sewer system

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 dry dry rings

 one
 - - - - 100 100 100 100

 2
 Polymer B 0.100 - - 96.3 95.7 100.9 98

 3
 Polymer B 0.300 - - 102.5 104.0 112.4 137

 4
 - - Polymer D * 0.100 104.5 108.6 107.1 109

 5
 - - Polymer D * 0.300 105.7 107.4 106.0 115

 6
 Polymer B 0.100 Polymer D * 0.100 100.8 95.2 105.6 134

 7
 Polymer B 0.300 Polymer D * 0.100 110.1 109.9 116.6 120

 8
 Polymer B 0.200 Polymer D * 0.200 112.9 115.8 119.9 118

 9
 Polymer B 0.100 Polymer D * 0.300 115.7 123.0 113.7 115

 10
 Polymer B 0.300 Polymer D * 0.300 110.4 120.2 111.3 112

* Reference number

Table 3 demonstrates that, with high dosages of the two poKmeros, excellent resistance performance can be achieved when the two chemicals are added together compared to their performance when added alone. This method allows the paper manufacturer to achieve greater efficiency in the use of chemicals and the added resistance achieved when the two chemicals are added together allows the paper manufacturer to reduce the use of the expensive Polymer B containing vinylamine. It is noted that the dosages normally used for dry strength polymers in the pilot papermaking machine are much larger (i.e. at least double) than comparable dosages from an efficiency point of view in a machine manufacturing commercial paper For example, if 0.10% of additive is an effective amount for a dry strength polymer in the pilot papermaking machine, then the effective amount in the commercial machine will be approximately 0.05% or less.

EXAMPLE 4

Table 4 shows a pilot papermaking machine test using an amphoteric polymer containing acrylamide in combination with the polymer containing vinylamine. This test was performed under conditions similar to those of Example 3 above. However, in this case, the amphoteric polymer C containing acrylamide was used instead of the reference cationic polymer D containing acrylamide.

Table 4. Results of a pilot papermaking machine test with Polymer B and Amphoteric Polymer C containing acrylamide.

 Entry
 Additive 1% Additive 2% Dry traction Dry Mullen burst Ring crush Drainage

 one
 - - - - 100 100 100.0 100

 2
 Polymer B 0.100 - - 98.9 - 102.2 105

 3
 Polymer B 0.300 - - 104.3 123.5 108.0 143

 4
 - - Polymer C 0.100 100.4 103.0 102.4 102

 5
 - - Polymer C 0.300 100.9 101.9 103.9 109

 6
 Polymer B 0.100 Polymer C 0.100 102.1 108.1 104.1 95

 7
 Polymer B 0.300 Polymer C 0.100 101.2 116.4 110.7 142

 8
 Polymer B 0.200 Polymer C 0.200 103.3 112.3 109.8 119

 9
 Polymer B 0.100 Polymer C 0.300 103.0 112.8 105.3 105

 10
 Polymer B 0.300 Polymer C 0.300 106 107.9 117.4 131

Table 4 shows that treatment with the two tandem polymers can especially enhance Mullen bursting and ring crushing versus the use of polymers in isolation. Drainage performance was only marginally affected. It is noted that the dosages normally used for dry strength polymers in the pilot papermaking machine are much larger (i.e. at least double) than comparable dosages from an efficiency point of view in a machine manufacturing commercial paper For example, if 0.10% of additive is an effective amount for a dry strength polymer in the pilot papermaking machine, then the effective amount in the commercial machine will be approximately 0.05% or less.

REFERENCE EXAMPLE 5.

Table 5 shows the effect of combining polymers in aqueous dispersion with Polymer B containing vinylamine. Table 5. Addition of the reference polymers in aqueous dispersion F and G to Polymer B to improve strength.

 Entry
 Additive 1% Additive 2% Traction Mullen Burst in Crush Drain

 dry dry or in rings

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 one
 - - - - 100 100 100 100

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 Poftmero B 0.100 - - 99.0 107.6 105.4 117

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 Poftmero B 0.300 - - 101.8 109.8 107.7 138

 4
 - - Poftmero F * 0,100 101.0 105.3 104.0 124

 5
 - - Poftmero F * 0.300 102.8 102.4 110.6 155

 6
 Poftmero B 0.100 Poftmero F * 0.100 97.5 104.6 104.1 136

 7
 Poftmero B 0.300 Poftmero F * 0.100 104.2 111.8 111.0 135

 8
 Poftmero B 0.200 Poftmero F * 0.200 104.1 116.9 110.7 140

 9
 Poftmero B 0.100 Poftmero F * 0.300 105.5 110.4 109.1 157

 10
 Poftmero B 0.300 Poftmero F * 0.300 108.3 119.2 114.6 125

 eleven
 - - Poftmero G * 0.300 98.6 98.4 102.2 123

 12
 - - Poftmero G * 0.300 99.5 102.3 101.2 151

 13
 Poftmero B 0.100 Poftmero G * 0.100 101.1 101.0 106.7 134

 14
 Poftmero B 0.300 Poftmero G * 0.100 104.9 118.5 108.9 142

 fifteen
 Poftmero B 0.200 Poftmero G * 0.200 103.6 114.8 110.2 145

 16
 Poftmero B 0.100 Poftmero G * 0.300 105.4 109.7 106.7 153

 17
 Poftmero B 0.300 Poftmero G * 0.300 107.2 130.0 111.7 139

* Reference number

Table 5 demonstrates that drainage can be maintained while significantly improved levels of dry strength are achieved with water dispersion poftmeros. It is noted that the dosages normally used for dry strength poftmeros in the pilot papermaking machine are much larger (i.e. at least double) than comparable dosages from an efficiency point of view in a machine manufacturing commercial paper For example, if 0.10% of additive is an effective amount for a dry strength polymer in the pilot papermaking machine, then the effective amount in the commercial machine will be approximately 0.05% or less.

EXAMPLE 6

Table 6 shows the combination of Poftmero B containing vinylamine with an amphoteric polyelectrolytic complex containing acrylamide, Poftmero H.

Table 6. Testing in pilot papermaking machine using an amphoteric polyelectrolytic complex containing acrylamide (Poftmero H) with Poftmero B.

 Entry
 Poftmero B added (%) Poftmero H added (%) Dry traction Burst Mullen dry Crushing rings

 one
 0.0 0.0 100 100 100

 2
 0.0 0.2 99.9 100.8 100.6

 3
 0.0 0.4 101.1 104.0 102.9

 4
 0.0 0.6 98.2 103.6 101.5

 5
 0.1 0.0 93.2 97.7 97.0

 6
 0.1 0.2 96.6 93.8 100.9

 7
 0.1 0.4 102.4 102.9 100.9

 8
 0.1 0.6 102.0 103.5 102.3

 9
 0.2 0.0 96.6 97.8 101.4

 10
 0.2 0.2 101.8 107.3 109.1

 eleven
 0.2 0.4 109.2 109.5 110.8

 12
 0.2 0.6 110.4 114.4 112.4

 13
 0.3 0.0 97.5 102.4 105.3

 14
 0.3 0.2 107.4 116.0 112.6

 fifteen
 0.3 0.4 115.6 122.1 115.1

 16
 0.3 0.6 114.7 121.6 116.2

Table 6 shows that results comparable to those of amphoteric poftmeros containing acrylamide can be achieved using the amphoteric polyelectrolytic complex containing acrylamide. Excellent levels of dry strength were achieved, at levels of additive at which the yield normally begins to level off. It is noted that the dosages normally used for dry strength poftmeros in the pilot papermaking machine are much larger (i.e. at least double) than comparable dosages from an efficiency point of view in a machine manufacturing commercial paper For example, if 0.10% of additive is an effective amount for a dry strength polymer in the pilot papermaking machine, then the effective amount in the commercial machine will be approximately 0.05% or less.

REFERENCE EXAMPLE 7

Table 7 shows the results of dry strength and drainage tests using an individual product mixture of Reference Powder K and Polymer B. Regardless of the relationship between the two polymers of the mixture, the additive was used at a level of 0.3% dosage versus dry paper pulp.

Table 7. Use of an individual product blend of Reference Polymer K and Polymer B to achieve improved dry strength

 Entry
 Polymer K: Polymer B Active solids (%) Dry traction Burst Mullen dry Crush rings Ring wet traction Drainage

 one
 0: 4 12.7 101.9 105.5 108.6 373.7 159.6

 2
 1: 3 14.6 105.7 110.7 109.4 347.9 149.0

 3
 1: 1 17.2 107.9 108.7 108.0 297.5 127.2

 4
 3: 1 20.8 108.2 108.8 109.7 200.9 109.0

10 Table 7 illustrates that the use of an individual product blend of a vinylamine-containing polymer and an acrylamide-containing cationic polymer can provide improved dry strength results in the dry tensile and dry Mullen burst categories, while crushing results are offered on comparable rings. The individual product mixture is especially useful because it offers the paper manufacturer the ease of adding an individual product to the papermaking machine, although the different ratios of the mixture 15 allow the product to be adjusted to the needs of the paper manufacturer. For example, if lower wet strength is necessary to reduce reprocessing energy, a mixture of individual product can be produced that meets that need while maintaining or improving dry strength properties. Or, if the papermaking machine is already running near its maximum speed, the amount of drainage provided by the product can be matched with the need of the paper manufacturer without compromising dry strength 20. In addition, the individual product mixture may have a significantly higher active solids content without this having a negative impact on dry strength, thereby reducing the ecological impact due to the transport of the solids content load to the paper mill. .

Claims (9)

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  9. 10.
    Process for the production of paper, cardboard and cardboard with improved dry strength comprising adding to the wet end of a papermaking machine
    (a) an aqueous solution polymer containing vinylamine having a molecular weight of from 75,000 daltons to 750,000 daltons and
    (b) an amphoteric aqueous solution polymer containing acrylamide having a molecular weight from 75,000 daltons to 1,500,000 daltons, in which the sum of the anionic and cationic monomers incorporated into the acrylamide-containing polymer comprise from 5% to 50% on a molar basis of all monomers incorporated into the acrylamide-containing polymer,
    wherein the polymer in aqueous solution is a polymer that forms a completely homogeneous solution in water when diluted to 1% on a dry solids basis.
    The method according to claim 1, wherein the total polymer solids content of the polymer in aqueous solution containing vinylamine is from 5% to 30% on a dry weight basis and wherein the vinylamine containing polymer has a W-vinylformamide content of at least 50% on a molar basis of the total monomer charged before hydrolysis and at least 10% of the W-vinylformamide has been hydrolyzed in the final polymer.
    The process according to claim 1, wherein the vinylamine-containing polymer has a molecular weight from 150,000 daltons to 500,000 daltons.
    The process according to claim 1, wherein the acrylamide-containing aqueous solution polymer is an aqueous dispersion polymer, preferably an aqueous dispersion polymer having a molecular weight from 300,000 daltons to 1,500,000 daltons, more preferably a polymer in an aqueous dispersion having a molecular weight from 400,000 daltons to less than 1,250,000 daltons, in which the aqueous dispersion polymer is a polymer produced by aqueous dispersion polymerization.
    The method according to claim 1, wherein the acrylamide-containing aqueous solution polymer comprises at least one cationic monomer selected from the group consisting of: diallyldimethylammonium chloride (DADMAC), 2- (dimethylamino) ethyl acrylate, methacrylate 2 - (dimethylamino) ethyl, 2- (diethylamino) ethyl acrylate, 2- (diethylamino) ethyl methacrylate, 3- (dimethylamino) propyl acrylate, 3- (dimethylamino) propyl methacrylate, 3- (diethylamino) propyl acrylate , 3- (diethylamino) propyl methacrylate, W- [3-
    (dimethylamino) propyl] acrylamide, W- [3- (dimethylamino) propyl] methacrylamide, W- [3- (diethylamino) propyl] acrylamide, W- [3- (diethylamino) propyl] methacrylamide, [2- (acryloxyloxy] chloride ) ethyl] trimethylammonium chloride, [2-
    (methacryloxy) ethyl] trimethylammonium, [3- (acryloyloxy) propyl] trimethylammonium chloride, [3-] chloride
    (methacryloxy) propyl] trimethylammonium, 3- (acrylamidopropyl) trimethylammonium chloride and 3- (methacrylamidopropyl) trimethylammonium chloride.
    The process according to claim 1, wherein the acrylamide-containing aqueous solution polymer has a molecular weight from 75,000 daltons to 750,000 daltons.
    The method according to claim 1, wherein the amphoteric aqueous solution polymer containing acrylamide is composed of a polyelectrolytic complex containing a polymer containing cationic, amphoteric or anionic filler acrylamide and a second complementary filler polymer.
    The method according to claim 7, wherein the polyelectrolytic complex has a molecular weight from 100,000 daltons to less than 1,000,000 daltons.
    The method according to claim 1, wherein the vinylamine-containing polymer and the acrylamide-containing polymer are added to the papermaking machine as a mixture of individual product.
    The method according to claim 9, wherein the cationic part of the acrylamide-containing polymer is generated from at least one monomer selected from the group consisting of diallyldimethylammonium chloride (DADMAC), W- [3- (dimethylamino) propyl] acrylamide, W- [3- (dimethylamino) propyl] methacrylamide, W- [3- (diethylamino) propyl] acrylamide, W- [3- (diethylamino) propyl] methacrylamide, 3- chloride
    (acrylamidopropyl) trimethylammonium and 3- (methacrylamidopropyl) trimethylammonium chloride, preferably generated from at least one monomer selected from the group consisting of diallyldimethylammonium chloride (DADMAC), W- [3- (dimethylamino) propyl] acrylamide, W - [3- (dimethylamino) propyl] methacrylamide, 3- (acrylamidopropyl) trimethylammonium chloride and 3- (methacrylamidopropyl) trimethylammonium chloride.
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