MXPA00000326A - Method for reducing the polymer and bentonite requirement in papermaking - Google Patents

Abstract

The present invention relates to a method for reducing the polymer and bentonite requirement in papermaking wherein medium and high molecular weight polymers are reacted with bentonite. Further, mechanical shearing of the furnish after polymer addition is not required.

Description

"A METHOD TO REDUCE THE REQUIREMENT OF POLYMER AND BENTONITE-IN PAPER MANUFACTURE" FIELD OF THE INVENTION The present invention relates to a method for reducing the polymer and bentonite requirement in papermaking wherein the medium and high molecular weight polymers are reacted with bentonite. In addition, a mechanical shear stress of the supply is not required after the addition of the polymer.

BACKGROUND OF THE INVENTION Economy and quality are concerns in the technique of papermaking. Those skilled in the art are always seeking to bring these two particularities of the papermaking process to the optimum. The basic papermaking process is known to those skilled in the art.

For reasons of completion we present here a general description of the paper manufacturer's technique. The material from which the paper is made will be called "supply". The supply is mostly a fibrous material to which mineral fillers or fillers are sometimes added, and chemical additives. The most common fibrous material is pulp or wood pulp. Pastures, cotton and synthetic materials are occasionally used. The wood is made up of fibers (cells) that are retained together with lignin. Pulp or wood pulp is manufactured either by separating the fibers mechanically or mechanically. The different methods provide variations in quality. The pulp or chemical wood pulp is typically of high quality. It has long smooth fibers, but it is expensive to produce. The pulp or mechanical pulp is less expensive. The fibers are shorter, often with a very rough surface. Recycled pulp or pulp is made by forming a slurry of waste paper in water. The fibers come out shorter and more degraded than they were originally. A variety of methods are used to whiten whiter fibers, and remove contaminants. Some of these methods also degrade the fibers. Extremely short fibers are called "thin" and are less than 1/100 of 2.54 centimeters long. The fines can amount to more than 50 percent of the total fiber. The pulp of wood pulp or supplies is transferred to the paper machine as a slurry of approximately 4 percent fiber and 96 percent water and is called "thick material". Mineral fillers can be added to this slurry. A typical addition is 10 percent of the filler or filler, which is commonly either kaolin clay or calcium carbonate (e.g., clay). These filler or filler materials are very small particles typically around the size of an icron. Chemicals are then added to improve paper properties, such as physical strength, water or color resistance. At this point, the supply is ready to be added to the paper machine. In order to manufacture the paper, the supply is further diluted to approximately 1.0 percent solids. This is referred to as "thin material". The "thin material" goes through the sieves and cleaners that impart a large amount of shear stress in the slurry. The "thin material" then goes to the "head box" that supplies the slurry to a movable "forming" or "wire" fabric. After the supply is placed in the forming fabric or "wire", most of the water is removed by gravity and vacuum. The fines (large amount of mechanical and recycled fiber) and all the filling or loading material are small enough to pass through the fabric or "wire". In order to keep these particles in the paper, they must flocculate into larger particles. While they are in the "wire" the solids content rises up to about 15 percent. The paper is then passed through presses that squeeze more water outward to provide solids of approximately 40 to 50 percent. Systems that use high molecular weight polymers provide good dehydration in the wire, but they frequently retard dehydration in the press section. The final water removal stage uses steam dryers. A very small change in the removal of water in the press section makes a considerable difference in the section of the dryer. The dryer section is the largest part of the machine, and typically limits the production rate. Those skilled in the art of papermaking are always looking for wood to improve the papermaking process. Specifically, U.S. Patent No. 4,305,781, assigned to Allied Colloids Limited, discloses a method for making paper with improved drainage and retention properties of a cellulosic suspension. The method involves the addition of polymers having a molecular weight of more than 500,000 to about 1,000,000, or greater - - (column 3, lines 8 to 13) to the suspension. The polymers used must be essentially non-ionic such as polyacrylamides (column 3, lines 14 to 16 and lines 27 to 33). The polymer is added to the suspension after the last high shear point prior to sheet formation (column 3, lines 66 to 68). The bentonite is added to the slurry in the thick material, the hydroreducer to pulp, or the white recirculating water (column 4, lines 3 to 8). The bentonite must be added before the polymer and at least one point of shear stress will occur between the addition of the bentonite and the polymer. The patent does not disclose the formation of small flocs. U.S. Patent No. 5,015,334 assigned to Laporte Industries Limited discloses a colloidal composition and its use in the production of paper and paperboard (column 1, lines 9 to 11). The patent discloses that a polymer can be added to the paper material followed by the addition of bentonite to the paper material without shear between the addition of the polymer and the bentonite (column 2, lines 38 to 52 and column 4, lines 19). to 29). The polymer used is a low molecular weight, water soluble, high charge density polymer having a molecular weight of less than 100,000 (column 3, lines 12 to 25).

Although the patent discloses that the shear stress is excluded between the addition of the polymer and the bentonite in the treatment of the paper material, the patent does not disclose the formation of small flocs as the present invention. Also, the patent uses low molecular weight polymers, non-polymers of medium molecular weight, ie from 100,000 to 2,000,000 as the process of the present invention. U.S. Patent No. 5,393,381 assigned to S N F, of France, discloses a process for the manufacture of paper or paperboard having improved retention properties (column 1, lines 6 to 8). The process involves adding a high molecular weight branched polymer such as a polyacrylamide (column 2, lines 43 to 56) to the pulp or paper pulp followed by shear stress of the mixture (column 3, lines 28 to 34) then adding the bentonite to the mixture (column 3, lines 34 to 37). The high molecular weight branched polymers are used because these polymers best retain the bentonite on a paper sheet of the unbranched polymers (column 2, lines 14 to 23). The patent does not disclose the use of specific medium molecular weight branched polymers of the present invention. In addition there is no discussion of the formation of small flocs. Also, the patent employs a - - Shear stress process between the addition of the polymer and the bentonite to the pulp or pulp unlike the present invention which eliminates the shear process. U.S. Patent No. 5,676,796 assigned to Allied Colloids Limited discloses a method for making paper or paperboard (column 1, lines 1 to 5). The method is aimed at improving the retention, drainage, drying and forming properties in papermaking (column 3, lines 42 to 51). The process involves forming a suspension of thick and flocculated cellulose material (column 3, lines 54 to 61 and column 4, lines 4 to 8) with a first polymer (column 6, lines 64 to 67 and column 7, line 1 to 7) . The first polymer used can be a low ionic polymer, a nonionic polymer and a low and medium cationic polymer (column 9, lines 63 to 67 and column 10, lines 1 to 6). The thick material is then diluted to form a thin material (column 3, lines 62 to 63). The large flocs are then formed into small dense flocs in the thin material, by adding a coagulant such as a nonionic polymer having a molecular weight of less than 1,000,000 or 500,000 (column 4, lines 8 to 14, column 7, lines 8 to 33 and column 11, lines 42 to 51). In addition, of the first and second polymers, bentonite can be inhibited either before, with or after the addition of the flocculating polymer (column 6, lines 50 to 63). Preferably, the bentonite is added after the addition of the second polymer to the thin material (column 4, lines 20 to 24). Before adding the bentonite, the material is subjected to shear stress (column 6, lines 58 to 63 and column 12, lines 36 to 39). While US Pat. No. 5,676,796 discloses the formation of small flocs by adding a polymer having a molecular weight of less than 1,000,000, the method of the present invention employs a medium molecular weight polymer to form small flocs without the formation of flocs. large by high molecular weight polymers, as disclosed in U.S. Patent No. 5,676,796. The present invention employs some high molecular weight polymers only to maintain the stability of small flocs. In addition, the method disclosed in US Patent Number 5,676,796 always employs shear stress before adding the bentonite. In contrast, the present invention does not employ shear stress between the addition of the polymer and the bentonite to the papermaking furnish. The invention of the applicants improves the technique because their program uses less polymer than a conventional bentonite program, it improves the - - dehydration of the press section that increases the solids that go to the dryers and reduces the drying requirements. In addition, a less shear stress step is required.

DEFINITIONS AND USE OF THE TERMS The term "supply", as used herein, means a material which is mostly fibrous, to which mineral fillers or fillers and chemical additives are sometimes added. The most common fibrous material is wood pulp or pulp. Pastures, cotton and synthetic materials are used occasionally. The term "bentonite", as used herein, means an activated alkaline montmorillonite or a similar clay, such as hectorite, nontrite, saponite, sauconite, beidelite, alevardite, halloisite and attapulgite. The bentonite clay should swell in water to expose the maximum surface area. If the clay does not naturally swell, it must be activated or converted into its sodium or potassium or ammonium form. This type of activation is obtained by treating the clay with a base such as sodium or potassium carbonate.

- The term "copolymer", as used herein, means a polymer produced from more than one type of monomer. The term "homopolymers", as used herein, means a polymer produced from a single type of monomer. The term "floccula", as used herein, means: an agglomeration of long, fine fibers and fillers or fillers. The term "retention", as used herein, means that portion of the solid phase of the supply that is retained in the forming fabric (ie, wire). The term "first pass ash retention", as used herein, means the amount of ash retained in the wire as compared to the total amount of ash supplied to the wire. The term "charge density", as used herein, means the amount of positive electric charge relative to the mass of the polymer. The term "Canadian Normal Refining (CSF)", as used herein, means a regime measure at which the pulp or pulp will allow the water to drain freely; it is an indication of the relative amounts of long and short fibers in the supply.

COMPENDIUM OF THE INVENTION The present invention relates to a method for improving the retention and drainage of the papermaking supply comprising the steps of: a. adding 0.005 percent to 0.25 percent by weight of at least one high molecular weight cationic charge density polymer of 100,000 to 2,000,000 having a charge density in excess of 4.0 Meq. to supply, after all the high shear points to form small flocs that have a size scale of less than 6.35 millimeters; b. add from 0 percent to 0.20 percent by weight of at least one polymer that has a molecular weight greater than 2,000,000 and a charge density of less than 4.0 Meq; c. add 0.025 percent to 2.0 per cent by weight of bentonite clay capable of swelling in water; The present invention furthermore relates to a method for improving the retention and drainage of the papermaking supply comprising the steps of: a. adding 0.005 percent to .25 weight percent of at least one high molecular weight cationic charge density polymer of 100,000 to 2,000,000 having a charge density in excess of 4.0 Meq. which are selected from the group consisting of cross-linked polyethylene imine homopolymers or copolymers or polymers produced from ethylene imine, amidoamine, acrylamide, epichlorohydrate, diallyldimethylammonium halides, allylamines, etheramines, vinylamines, vinyl-heterocycles, N-vinylimidazole and methylacrylates, upon delivery, after of all high shear points, the high shear stress occurring prior to the addition of the polymer to form small flocs having a size scale of less than 6.35 millimeters in diameter; adding from 0 percent to 0.20 percent by weight of at least one polymer having a molecular weight greater than 2,000,000 having a charge density of less than 4.0 Meq that is selected from the group consisting of polyacrylamides produced by copolymerizing acrylamide and / or methacrylamide with anionic monomers such as acrylic acid, methacrylic acid, maleic acid, vinylsulfonic acid or cationic monomers such as C] _- or C2 alkylamino-C2-C4alkyl (meth) acrylates, diethylamino-ethyl acrylate, diethylaminoethyl methacrylate, dimethylaminopropyl acrylate , dimethyl-aminobutyl acrylate, - dimethylaminopentyl acrylate and corresponding methacrylates; c. add 0.025 percent to 2.0 percent by weight of a thick hydrated slurry of a bentonite clay capable of swelling. All dosages are based on the dry polymer or the pigment as a percentage by weight (% by weight) of dry supply unless otherwise indicated.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for improving the retention and drainage of the papermaking supply, comprising the steps of: a. adding from 0.005 percent to 0.25 percent by weight of at least one high molecular weight cationic charge density polymer of 100,000 to 2,000,000 having a charge density in excess of 4.0 Meq to the supply, after all the points of high shear stress, in order to form small flocs that have a size scale of less than 6.35 millimeters in diameter; b. add from 0 percent to 0.20 percent by weight of at least one polymer that has a molecular weight - greater than 2,000,000 and a load density of less than 4. 0 Meq; c. add from 0.025 percent to 2.0 percent by weight the bentonite clay capable of swelling in water; The present invention further relates to a method for improving the retention and drainage of the papermaking supply, comprising the steps of: a. adding 0.005 percent to .25 weight percent of at least one high molecular weight cationic charge density polymer of 100,000 to 2,000,000 having a charge density in excess of 4.0 Meq which is selected from the group consisting of crosslinked polyethylene imine homopolymers or copolymers or polymers produced from ethylene imine, amidoamine, acrylamide, epichlorohydrate, diallyldimethylammonium halides, allylamines, etheramines, vinylamines, vinyl heterocycles, N-vinylimidazole and methylacrylates, upon delivery, after all high shear points , the high shear stress occurring before the addition of the polymer to form small flocs having a size scale of less than 6.35 millimeters in diameter; b. adding 0 percent to 0.20 percent by weight of at least one polymer having a molecular weight greater than 2,000,000 having a charge density of less than 4.0 Meq that is selected from the group consisting of polyacrylamides that are produced by copolymerizing acrylamide and / or methacrylamide with anionic monomers such as acrylic acid, methacrylic acid, maleic acid, vinylsulfonic acid or cationic monomers such as C? _ or C2 alkylamino-C2-C alkyl (meth) acrylates, diethylamino-ethyl acrylate, diethylaminoethylmethacrylate, dimethylaminopropyl acrylate, dimethyl-aminobutyl acrylate, dimethylaminopentyl acrylate and the corresponding methacrylates; c. add 0.025 percent to 2.0 percent by weight of a thick hydrated slurry of a bentonite clay capable of swelling. All dosages are based on a dry polymer or pigment as a percentage by weight of the dry supply, unless otherwise indicated.

THE PRACTICE OF THE PRESENT INVENTION STEP a: Any cationic polymer with charge density greater than 4.0 Meq, and molar mass in excess of 100,000 can be used as the medium molecular weight polymer in Step 1 of the present invention. The selection of the appropriate medium molecular weight cationic polymer is critical. There are two operating factors that must be taken into account. A considerable difference in retention and drainage has been observed among the polymers. In addition, some types of polymer control the additional flocculation level of the high molecular weight polymer much better than others. Improved overall performance typically occurs with increased charge density, molecular weight and significant branching or crosslinking in the polymer chain. Preferred polymers include those with filler densities of 6.0 Meq or higher, and molecular weight in excess of 250,000. Especially preferred are those polymers containing ethyleneimine or amidoamine with molecular weight in excess of 500,000. Especially preferred polymers are the modified polyethylene imine polymers which are crosslinked polyethylene imine and amidoamine graft copolymers to form a highly branched structure such as POLYMIN® SKA obtainable from BASF, of Mt. Olive, New Jersey. The POLYMIN® products have a molecular weight of approximately 1,200,000 and a charge density within the range of 8 to 14 Meq at 4.5 pH.

- - The cationic medium molecular weight polymer is used at levels of 0.005 percent to 0.25 percent by weight. The preferred level of use is from 0.01 percent to 0.2 percent by weight, the level of use especially preferred is from 0.015 percent to 0.15 percent by weight. The level of use that is especially preferred is 0.02 percent to 0.10 percent by weight. When the forming section of the paper machine has only low to moderate shear stress, the high charge density cationic polymer from Step a, followed by bentonite, will normally be sufficient. Under conditions of higher shear stress, microflocles formed by the high charge density cationic polymer may not have sufficient stability. A second polymer must now be added. This is Step b, of the present invention.

STEP b: The polymer (s) used in Step b can be any polymer with a molecular weight in excess of 2 million, and which is reactive to the supply. Typically, dosages of less than 0.1 weight percent will be used. The preferred level is from 0.001 percent to 0.1 percent by weight. The especially preferred level is from 0.01 percent to .06 percent by weight. The preferred products - they are polyacrylamides with a molecular weight of 4 million or more. cationic acrylamides are especially preferred and those especially preferred are cationic acrylamides with a charge density of less than 4.0 Meq, preferably between 0.8 and 2.5 Meq. An example of a suitable high molecular weight polymer is Polymin® KE78 (cationic polyacrylamide) from BASF AG, Ludwigshafen, Germany. Typically, Step a. precedes Step b. However, it is often possible to premix the polymers from Step a. and b. and use a single point of addition. The two polymers must of course be compatible for this type of application. The use of this simultaneous addition technique is especially well suited when using a combination of modified polyethyleneimine and cationic polyacrylamide. In this case, not only the addition of the polymer is simplified, but a slight improvement in the efficiency of the polymer is often observed.

STEP c: After the microflocls are formed, the bentonite clay is added to the supply, the normal application rate is 0.025 percent to 2.0 percent by weight based on the solids in the supply. Preferred application regimes are from 0.05 percent to 1.5 percent by weight and more preferably from 0.1 percent to 1.0 percent by weight and especially preferred are from 0.2 percent to 0.5 percent by weight. The bentonite clay can be any silicate having charged sites capable of reacting with the polymer. The preferred clay is an activated alkaline montmorillonite or similar clay such as hectorite, nontrite, saponite, sauconite, beidelite, alevardite, halloysite and attapulgite. Montmorillonite clays are especially preferred and those most preferred are those which exhibit considerable viscosity when formed in a slurry in water at a solids content of 5 percent to 10 percent and allowed to age. An example of this type of product is Opazil® NH from BASF Corp. Bentonite clay should swell in water (hydrate) to expose a maximum surface area. This occurs after the pigment is formed in slurry thickened in water and allowed to age. The aging process typically requires 30 to 150 minutes. If clay does not naturally swell, it must be activated or converted into its sodium, potassium or ammonium form. This type of activation is obtained by treating the clay with a base such as sodium or potassium carbonate. The application of shear stress to the slurry can reduce the time required for some clays to swell.

- The point of application for the bentonite is after the polymer has been mixed with the supply. This will typically be just before the head box or tub. Optimum results are obtained when there are no shear points between or after polymer and bentonite applications.

OPTIONAL INGREDIENTS Some papermaking systems have high levels of contaminants in the water circuit. These contaminants are typically anionic materials in either a colloidal or a solution state. Some examples include wood resins, deposit control agents, pulp or pulping, bleaching or chemicals, waste paper contaminants and single acid. In the case of intensely contaminated systems, it may be preferred to pre-treat the supply with at least one anionic cleaner. The anionic cleaner can be any cationic substance. Preferred substances have a high cationic charge such as aluminum-containing compounds including, but not limited to, aluminum sulfate, polyaluminium chloride and / or high charge density (Meq> 6.0), cationic polymers such as polyethylene imine, polysaccharide, polyvinylamine or any - another cationic polymer of high charge density. Especially preferred are those polymers with a loading density of 8.0 Meq or higher. Polyethylenimine cationic polymers with a charge density of 10.0 Meq and a molecular weight of about 750,000 are especially preferred. An example of this type of product is Polymin® PL from BASF Corp. In some cases it may be possible to use the same polymer for charge neutralization, as used in Step a. This is done in order to simplify the number of products needed. If on the other hand a maximum polymer efficiency is sought, the anionic cleaner will typically be higher in the cationic charge and lower in molecular weight than the polymer in Step a. In addition, normal papermaking additives can typically be used in combination with this invention. This includes products that improve wet or dry strength, sizing or absorbency, reduce foam formation, bacterial growth or deposits as well as pigments or coloring agents. If any of the additives are highly anionic, it is usually preferred to add them with at least one point of shear stress between the additive and the cationic polymers.

THE FOLLOWING NON-LIMITATIONAL EXAMPLES ILLUSTRATE THE PRESENT INVENTION: Basic Laboratory Protocol: A mixture of soft kraft wood bleached at 50 percent with a Canadian Normal Refining (CSF) of 700, 40 percent by weight of pulp or thermomechanical pulp with a CSF of 10, and coated paper recycled at 10 percent percent is diluted to 0.6 percent by weight solids with white water. Alum is added to achieve a pH of 4.8. The supply (1000 milliliters) is treated with the polymer and then the bentonite is added in microparticles or colloidal silica (if any). The suspension is placed in a Modified Schopper Reigler (MSR) drain tester and the time required for 300 cubic centimeters of filtrate to drain is calculated. The solids in the filtered material are then determined by filtering the 300 cubic centimeters of the filtered material through a Watmann® Number 4 vacuum filter paper.

Example 1: Example 1 of the laboratory series was run with each polymer added at 0.025 weight percent and the activated bentonite added at 0.25 weight percent based on the dry product in the paper material. No shear was added in this first series of tests. The effect on the fines and the retention of the filling material is shown below Non-Retained Solids (mg) / 300 mg of filtered material Polymer Type Polymer only After Bentonite Without polymer 1270 1190 Modified polyethyleneimine 940 420 Po1iamido mine 1050 550 Polyethyleneimine 1070 510 PoliDADMAC 1230 670 Polyethylether amine 1140 710 As will be seen, the addition of bentonite clay after the high charge density polymer resulted in improved retention. The polymers are listed in descending molecular weight. The first three products are considerably branched, while the last two products were predominantly linear. The benefits of higher molecular weight and a branched configuration are evident.

Example 2: The following chemicals were used in these comparisons: Polymer A; Modified polyethyleneimine (Polymin® SK? From BASF Corp.) Polymer A which is produced by grafting the polyethylenimine into the polyamidoamine then reticulated to form a product with a slightly molecular weight of more than 1,000,000 and a cationic charge density of 9 Meq per gram, They are known as the dry product. Polymer B, a high molecular weight cationic polyacrylamide emulsion with a molecular weight of approximately 5,000,000 and a loading density of 1.8 Meq / gram (Polymin® PR8578 from BASF Corp). Microparticle C, activated bentonite clay (Opazil® NH by BASF Corp.) which is formed in slurry of an activated montmorillonite clay of sodium carbonate and water, and stirred slightly until it reaches the maximum viscosity. It is known as a dry product.

Microparticle D, colloidal silica dispersion, as received (MBA® 780 by Azko Nobel). Polymer E, a non-ionic polyacrylamide (Polymin® NP4 from BASF Corp.). Polymer F is polyethyleneimine with a molecular weight of 700,000 and a loading density of 20 Meq (Polymin® PR971L from BASF Corp). Unless otherwise stated, the order of addition is the polymer first, the shear stress (if applied) followed by the microparticle.

Test Polymer Effort Micropar- Time of Solids No Retention-Cutting Number ticula Drain two-mg / 300 mg of filtered material blank no none 178 1190 0. 02% A no nxnguna 149 1010 0. 02% B no none 147 750 0. 01% A 0. 01% B no 0.25% C 45 305 - 0. 02% B yes 0.25% C 143 920 0. 04% B yes 0.25% C 112 710 0. 06% B yes 0.25% C 53 265 0. 02% B 0.25% D 74 470 0. 03% B yes 0.50% D 42 320 0. 01% A 0. 01% B yes 0.25% C 460 0. 01% A 0. 01% B no 0.50% C 47 600 added first 0. 02% E not 0.50% C 64 640 added first In these tests, Test 12 is the organosorption system, as disclosed in US Patent Number 2,368,635, which is incorporated by reference herein, and Exhibit 11 is described in U.S. Patent No. 4,749,444, which is incorporated by reference herein. Both of these tests as well as Tests 2 and 3 (polymer only) provided insufficient retention. Test 9 is the optimized Composil® colloidal silica system, while Test 7 is the Hidrocol® bentonite system, as described in US Patent Number 5,676,796 which is incorporated by reference herein. Note that the present invention (Test 4) provides equivalent performance with significantly lower chemical applications. The flock size for Tests 4 and 7 was similar, while Test 9 had a slightly larger flock size. Test 10 indicates that the addition of the shear stress to the invention reduces the operation of the system.

Example 3: The benefits of using an anionic cleaner were investigated. The tests used the same supply as in Example 2, with the exception of Test # 4 and Test # 5 that suppressed the alum treatment. The polymers used were also the same as those used in Example 2, Polymer A is modified polyethyleneimine, Polymer B is cationic polyacrylamide and Polymer F is polyethyleneimine with a molecular weight of 700,000 and a loading density of 20 Meq (Polymin® PR971L from BASF Corp).

Test Polymer Effort Micropar- Time of Non-Retentive Solids # Cutting ticula Drain two, mg 0. 01% A 0. 001% B not 0.25% C 45 305 2 0.01% F 0. 01% A 0. #, 2, and 3, alum was added prior to the polymers at approximately 0.5 percent based on the dry supply. Tests # 2 used an anionic cleaner (Polymer F) in addition to alum. Test # 3 used an additional medium molecular weight polymer of the invention (Polymer A) instead of the anionic cleaner in Test # 2. The anionic cleaner improved retention and drainage in all four cases. Note that the slowest retention and the slowest drainage were obtained in Test # 4 that did not use anionic cleaner. Comparison Tests # 2 and # 3 reveal that using Polymer F to pre-treat the supply provided superior results to the use of the additional Polymer A. Comparing Test # 1 with Test # 5 indicates that the polymer as a neutralizer provides superior performance in relation to alum. However, the largest effect was observed in Tests # 2 and # 3 using both the polymer and the alum.

Example 4 (Plant Test): Further evidence of the superiority of the invention is shown in the following test data of the paper machine plant. The twin-wire machine was running light-weight coated paper at 1097.28 meters per minute using 44 percent thermo-mechanical pulp or pulp, and 56 percent soft-bleached kraft paper. The supply had been treated with alum and polyethyleneimine before the paper machine to neutralize and fix the harmful substances. The polymers (A, B and C) used are the same as those in the previous examples. The polymers were applied after the last point of high shear stress towards the discharge of the head box screens and the bentonite clay was added at an additional 4,572 meters downstream. The first pass ash retention was calculated - by the difference in the concentration of ash between the head box and the water of the tray divided by the concentration of the head box.

Normal Program Essay (Invention of the applicant) Retention Assistants 0.025% A 0.025% A 0. 02% B 0.02% B 0. 30% C Solids in the Tray 0.62% 0.53% Drain Time of the Headbox 134 sec. 109 sec.

Retention of First Pass Ash 28% 36% Training index 91 91 As will be seen, the invention improved retention and drainage without an increase in polymer flow. The formation of the leaf was not affected demonstrating that the appropriate chemical selection can modify the structure of the flock without the need of shear.

Claims (5)

R E I V I N D I C A C I O N S

1. A method for improving the retention and drainage of the papermaking supply comprising the steps of: a. adding from 0.005 percent to 0.25 percent by weight of at least one high molecular weight cationic charge density polymer of 100,000 to 2,000,000 having a charge density in excess of 4.0 Meq to the supply, after all the points of high shear stress to form small flocs that have a size scale of less than 6.35 millimeters in diameter; b. adding from 0 percent to 0.20 percent by weight at least one polymer having a molecular weight greater than 2,000,000 and a charge density of less than 4.0 Meq; c. add 0.025 percent to 2.0 percent by weight of a thick hydrated suspension of an inflatable bentonite clay.

2. A method for improving the retention and drainage of the papermaking supply comprising the steps of: a. adding from 0.005 percent to 0.25 percent by weight of at least one cationic polymer of high molecular weight charge density from 100,000 to 2,000,000 having a charge density in excess of 4.0 Meq to the supply, after all the points of high shear stress, in order to form small flocs that have a size scale of less than 6.35 millimeters in diameter; b. add from 0 percent to 0.20 percent by weight of at least one polymer having a molecular weight greater than 2,000,000 and a charge density of less than 4.0 Meq that is selected from the group consisting of polyacrylamides produced by copolymerizing acrylamide and / or methacrylamide with anionic monomers such as acrylic acid, methacrylic acid, maleic acid, vinylsulfonic acid or cationic monomers such as C] _- or C2 ~ alkylamino-C2-C4alkyl (meth) acrylates, diethylamino-ethyl acrylate, diethylaminoethylmethacrylate, dimethylaminopropyl acrylate , dimethyl-aminobutyl acrylate, dimethylaminopentyl acrylate and the corresponding methacrylates; c. add 0.025 percent to 2.0 percent by weight of a thick hydrated suspension of an inflatable bentonite clay.

3. A method for improving the retention and drainage of the papermaking supply comprising the steps of: a. adding from 0.005 percent to 0.25 weight percent of at least one high molecular weight charge cationic polymer of 100,000 to 2,000,000 having a charge density in excess of 4.0 Meq which is selected from the group consisting of homopolymers of crosslinked polyethyleneimine or copolymers or polymers produced from ethylene imine, amidoamine, acrylamide, epichlorohydrate, diallyldimethylammonium halides, allylamines, heteramines, vinylamines, vinyl-heterocycles, N-vinylimidazole and methacrylates to the supply, after all high shear points in order to of forming small flocs that have a size scale of less than 6.35 millimeters in diameter; b. add from 0 percent to 0.20 percent by weight of at least one polymer having a molecular weight greater than 2,000,000 and a charge density of less than 4.0 Meq that is selected from the group consisting of polyacrylamides produced by copolymerizing acrylamide and / or methacrylamide with anionic monomers such as acrylic acid, methacrylic acid, maleic acid, vinylsulfonic acid or cationic monomers such as C] _- or C2- alkylamino-C2-C4alkyl (meth) acrylates, diethylamino-ethyl acrylate, diethylaminoethyl methacrylate, dimethylaminopropyl acrylate , dimethyl-aminobutyl acrylate, dimethylaminopentyl acrylate and the corresponding methacrylates; c. add 0.025 percent to 2.0 percent by weight of a thick hydrated suspension of an inflatable bentonite clay.

4. A method according to claim 3, wherein the cationic high charge density polymer of Step a. is a graft copolymer of polyethyleneimine and amidoamine; wherein also, the polymer used in Step b. is a cationic acrylamide having a charge density of 0.8 to 2.5 Meq.

5. A method for improving the retention and drainage of a papermaking supply comprising the steps of: a. add one or more anionic cleaning substances that are selected from the group consisting of cationic polymers and aluminum-containing compounds; b. adding from 0.005 percent to 0.25 percent by weight of at least one cationic polymer of high molecular weight charge density from 100,000 to 2,000,000, which has a charge density in excess of 4.0 Meq to the supply, after all points of high shear stress, in order to form small flocs that have a size scale of less than 6.35 millimeters in diameter; c. adding from 0 percent to 0.20 percent by weight of at least one polymer having a molecular weight greater than 2,000,000 and a charge density of less than 4.0 Meq that are selected from the group consisting of polyacrylamides produced by copolymerizing acrylamide and / or methacrylamide with anionic monomers, such as acrylic acid, methacrylic acid, maleic acid, vinylsulfonic acid or cationic monomers such as C] _- or C2 * -alkylamino-C2-C4alkyl (meth) acrylates, diethylamino-ethyl acrylate, diethylaminoethylmethacrylate, acrylate of dimethylaminopropyl, dimethyl-aminobutyl acrylate, dimethylaminopentyl acrylate and the corresponding methacrylates; d. add 0.025 percent to 2.0 percent by weight of a thick hydrated suspension of an inflatable bentonite clay.